Experiment 5 · seaquest · fresh

YOUR TASK: write, from scratch, the weights of a policy network that plays this game as well as possible. There is no training: no data, no loss, no gradients, no fine-tuning; you choose every number yourself. You have no tools: no code execution, no calculator, nothing to run. This is a single response and you will get no feedback. First describe your design briefly (the strategy, and what the hidden units compute), then write the edits block.

THE GAME: Seaquest from MinAtar (Young & Tian 2019), on a 10 x 10 grid. The player steers a two-cell submarine (front and back) in all 4 directions and fires bullets from its front. Enemy fish and enemy submarines cross the screen; enemy submarines shoot. Hitting an enemy with a bullet gives +1. Divers can be picked up (up to 6; a bar along the bottom counts them). Oxygen runs down (another bar along the bottom) and is refilled by surfacing at the top row with at least one diver on board (surfacing with fewer than 6 removes one diver; with 6, all are removed and a bonus is paid). The episode ends when the submarine is hit, runs out of oxygen, or surfaces with no diver.
Actions: left, up, right, down move the submarine, fire shoots.

The game's exact implementation (the MinAtar package, version 1.0.15, file minatar/environments/seaquest.py) follows. The environment wrapper calls act(a) with a = 0..5 meaning 'n' (no-op), 'l', 'u', 'r', 'd', 'f' (this file's action_map), and with probability 0.1 it repeats the previous action instead of the new one (sticky actions). The observation the network gets is built from this file's state() as described under THE INPUT.

```python
################################################################################################################
# Authors:                                                                                                     #
# Kenny Young (kjyoung@ualberta.ca)                                                                            #
# Tian Tian (ttian@ualberta.ca)                                                                                #
################################################################################################################
import numpy as np


#####################################################################################################################
# Constants
#
#####################################################################################################################
ramp_interval = 100
max_oxygen = 200
init_spawn_speed = 20
diver_spawn_speed = 30
init_move_interval = 5
shot_cool_down = 5
enemy_shot_interval = 10
enemy_move_interval = 5
diver_move_interval = 5


#####################################################################################################################
# Env
#
# The player controls a submarine consisting of two cells, front and back, to allow direction to be determined. The
# player can also fire bullets from the front of the submarine. Enemies consist of submarines and fish, distinguished
# by the fact that submarines shoot bullets and fish do not. A reward of +1 is given each time an enemy is struck by
# one of the player's bullets, at which point the enemy is also removed. There are also divers which the player can
# move onto to pick up, doing so increments a bar indicated by another channel along the bottom of the screen. The
# player also has a limited supply of oxygen indicated by another bar in another channel. Oxygen degrades over time,
# and is replenished whenever the player moves to the top of the screen as long as the player has at least one rescued
# diver on board. The player can carry a maximum of 6 divers. When surfacing with less than 6, one diver is removed.
# When surfacing with 6, all divers are removed and a reward is given for each active cell in the oxygen bar. Each
# time the player surfaces the difficulty is increased by increasing the spawn rate and movement speed of enemies.
# Termination occurs when the player is hit by an enemy fish, sub or bullet; or when oxygen reached 0; or when the
# player attempts to surface with no rescued divers. Enemy and diver directions are indicated by a trail channel
# active in their previous location to reduce partial observability.
#
#####################################################################################################################
class Env:
    def __init__(self, ramping=True):
        self.channels ={
            'sub_front':0,
            'sub_back':1,
            'friendly_bullet':2,
            'trail':3,
            'enemy_bullet':4,
            'enemy_fish':5,
            'enemy_sub':6,
            'oxygen_guage':7,
            'diver_guage':8,
            'diver':9
        }
        self.action_map = ['n','l','u','r','d','f']
        self.ramping = ramping
        self.random = np.random.RandomState()
        self.reset()

    # Update environment according to agent action
    def act(self, a):
        r = 0
        if(self.terminal):
            return r, self.terminal

        a = self.action_map[a]

        # Spawn enemy if timer is up
        if(self.e_spawn_timer==0):
            self._spawn_enemy()
            self.e_spawn_timer = self.e_spawn_speed

        if(self.d_spawn_timer==0):
            self._spawn_diver()
            self.d_spawn_timer = diver_spawn_speed

        # Resolve player action
        if(a=='f' and self.shot_timer == 0):
            self.f_bullets+=[[self.sub_x, self.sub_y, self.sub_or]]
            self.shot_timer = shot_cool_down
        elif(a=='l'):
            self.sub_x = max(0, self.sub_x-1)
            self.sub_or = False
        elif(a=='r'):
            self.sub_x = min(9, self.sub_x+1)
            self.sub_or = True
        elif(a=='u'):
            self.sub_y = max(0, self.sub_y-1)
        elif(a=='d'):
            self.sub_y = min(8, self.sub_y+1)

        # Update friendly Bullets
        for bullet in reversed(self.f_bullets):
            bullet[0]+=1 if bullet[2] else -1
            if(bullet[0]<0 or bullet[0]>9):
                self.f_bullets.remove(bullet)
            else:
                removed = False
                for x in self.e_fish:
                    if(bullet[0:2]==x[0:2]):
                        self.e_fish.remove(x)
                        self.f_bullets.remove(bullet)
                        r+=1
                        removed = True
                        break
                if(not removed):
                    for x in self.e_subs:
                        if(bullet[0:2]==x[0:2]):
                            self.e_subs.remove(x)
                            self.f_bullets.remove(bullet)
                            r+=1
                            break

        # Update divers
        for diver in reversed(self.divers):
            if(diver[0:2]==[self.sub_x,self.sub_y] and self.diver_count<6):
                self.divers.remove(diver)
                self.diver_count+=1
            else:
                if(diver[3]==0):
                    diver[3]=diver_move_interval
                    diver[0]+=1 if diver[2] else -1
                    if(diver[0]<0 or diver[0]>9):
                        self.divers.remove(diver)
                    elif(diver[0:2]==[self.sub_x,self.sub_y] and self.diver_count<6):
                        self.divers.remove(diver)
                        self.diver_count+=1
                else:
                    diver[3]-=1

        # Update enemy subs
        for sub in reversed(self.e_subs):
            if(sub[0:2]==[self.sub_x,self.sub_y]):
                self.terminal = True
            if(sub[3]==0):
                sub[3]=self.move_speed
                sub[0]+=1 if sub[2] else -1
                if(sub[0]<0 or sub[0]>9):
                    self.e_subs.remove(sub)
                elif(sub[0:2]==[self.sub_x,self.sub_y]):
                    self.terminal = True
                else:
                    for x in self.f_bullets:
                        if(sub[0:2]==x[0:2]):
                            self.e_subs.remove(sub)
                            self.f_bullets.remove(x)
                            r+=1
                            break
            else:
                sub[3]-=1
            if(sub[4]==0):
                sub[4]=enemy_shot_interval
                self.e_bullets+=[[sub[0] if sub[2] else sub[0], sub[1], sub[2]]]
            else:
                sub[4]-=1

        # Update enemy bullets
        for bullet in reversed(self.e_bullets):
            if(bullet[0:2]==[self.sub_x,self.sub_y]):
                self.terminal = True
            bullet[0]+=1 if bullet[2] else -1
            if(bullet[0]<0 or bullet[0]>9):
                self.e_bullets.remove(bullet)
            else:
                if(bullet[0:2]==[self.sub_x,self.sub_y]):
                    self.terminal = True

        # Update enemy fish
        for fish in reversed(self.e_fish):
            if(fish[0:2]==[self.sub_x,self.sub_y]):
                self.terminal = True
            if(fish[3]==0):
                fish[3]=self.move_speed
                fish[0]+=1 if fish[2] else -1
                if(fish[0]<0 or fish[0]>9):
                    self.e_fish.remove(fish)
                elif(fish[0:2]==[self.sub_x,self.sub_y]):
                    self.terminal = True
                else:
                    for x in self.f_bullets:
                        if(fish[0:2]==x[0:2]):
                            self.e_fish.remove(fish)
                            self.f_bullets.remove(x)
                            r+=1
                            break
            else:
                fish[3]-=1

        # Update various timers
        self.e_spawn_timer -= self.e_spawn_timer>0
        self.d_spawn_timer -= self.d_spawn_timer>0
        self.shot_timer -= self.shot_timer>0
        if(self.oxygen<=0):
            self.terminal = True
        if(self.sub_y>0):
            self.oxygen-=1
            self.surface = False
        else:
            if(not self.surface):
                if(self.diver_count == 0):
                    self.terminal = True
                else:
                    r+=self._surface()
        return r, self.terminal

    # Called when player hits surface (top row) if they have no divers, this ends the game,
    # if they have 6 divers this gives reward proportional to the remaining oxygen and restores full oxygen
    # otherwise this reduces the number of divers and restores full oxygen
    def _surface(self):
        self.surface = True
        if(self.diver_count == 6):
            self.diver_count = 0
            r = self.oxygen*10//max_oxygen
        else:
            r = 0
        self.oxygen = max_oxygen
        self.diver_count -= 1
        if self.ramping and (self.e_spawn_speed>1 or self.move_speed>2):
            if(self.move_speed>2 and self.ramp_index%2):
                    self.move_speed-=1
            if(self.e_spawn_speed>1):
                    self.e_spawn_speed-=1
            self.ramp_index+=1
        return r

    # Spawn an enemy fish or submarine in random row and random direction,
    # if the resulting row and direction would lead to a collision, do nothing instead
    def _spawn_enemy(self):
        lr = self.random.rand() < 1/2
        is_sub = self.random.rand() < 1/3
        x = 0 if lr else 9
        y = self.random.randint(low=1, high=9)

        # Do not spawn in same row an opposite direction as existing
        if(any([z[1]==y and z[2]!=lr for z in self.e_subs+self.e_fish])):
            return
        if(is_sub):
            self.e_subs+=[[x,y,lr,self.move_speed,enemy_shot_interval]]
        else:
            self.e_fish+=[[x,y,lr,self.move_speed]]

    # Spawn a diver in random row with random direction
    def _spawn_diver(self):
        lr = self.random.rand() < 1/2
        x = 0 if lr else 9
        y = self.random.randint(low=1, high=9)
        self.divers+=[[x,y,lr,diver_move_interval]]

    # Query the current level of the difficulty ramp, could be used as additional input to agent for example
    def difficulty_ramp(self):
        return self.ramp_index

    # Process the game-state into the 10x10xn state provided to the agent and return
    def state(self):
        state = np.zeros((10,10,len(self.channels)),dtype=bool)
        state[self.sub_y,self.sub_x,self.channels['sub_front']] = 1
        back_x = self.sub_x-1 if self.sub_or else self.sub_x+1
        state[self.sub_y,back_x,self.channels['sub_back']] = 1
        state[9,0:max(0,self.oxygen)*10//max_oxygen, self.channels['oxygen_guage']] = 1
        state[9,9-self.diver_count:9, self.channels['diver_guage']] = 1
        for bullet in self.f_bullets:
            state[bullet[1],bullet[0], self.channels['friendly_bullet']] = 1
        for bullet in self.e_bullets:
            state[bullet[1],bullet[0], self.channels['enemy_bullet']] = 1
        for fish in self.e_fish:
            state[fish[1],fish[0], self.channels['enemy_fish']] = 1
            back_x = fish[0]-1 if fish[2] else fish[0]+1
            if(back_x>=0 and back_x<=9):
                state[fish[1],back_x, self.channels['trail']] = 1
        for sub in self.e_subs:
            state[sub[1],sub[0], self.channels['enemy_sub']] = 1
            back_x = sub[0]-1 if sub[2] else sub[0]+1
            if(back_x>=0 and back_x<=9):
                state[sub[1],back_x, self.channels['trail']] = 1
        for diver in self.divers:
            state[diver[1],diver[0], self.channels['diver']] = 1
            back_x = diver[0]-1 if diver[2] else diver[0]+1
            if(back_x>=0 and back_x<=9):
                state[diver[1],back_x, self.channels['trail']] = 1

        return state

    # Reset to start state for new episode
    def reset(self):
        self.oxygen = max_oxygen
        self.diver_count = 0
        self.sub_x = 5
        self.sub_y = 0
        # 0=left, 1=right
        self.sub_or = False
        self.f_bullets = []
        self.e_bullets = []
        self.e_fish = []
        self.e_subs = []
        self.divers = []
        self.e_spawn_speed = init_spawn_speed
        self.e_spawn_timer = self.e_spawn_speed
        self.d_spawn_timer = diver_spawn_speed
        self.move_speed = init_move_interval
        self.ramp_index = 0
        self.shot_timer = 0
        self.surface = True
        self.terminal = False

    # Dimensionality of the game-state (10x10xn)
    def state_shape(self):
        return [10,10,len(self.channels)]

    # Subset of actions that actually have a unique impact in this environment
    def minimal_action_set(self):
        minimal_actions = ['n','l','u','r','d','f']
        return [self.action_map.index(x) for x in minimal_actions]

```

THE INPUT (600 numbers, each 0 or 1): the 10 x 10 grid (rows 0 top to 9 bottom, columns 0 left to 9 right) with 6 channels. Input number i = (row * 10 + column) * 6 + channel; for example input 0 is (row 0, column 0, channel 0), input 6 is (row 0, column 1, channel 0) and input 599 is (row 9, column 9, channel 5). In this game:
  channel 0 (player): the submarine (front and back cells)
  channel 1 (danger): enemy fish, enemy submarines and enemy bullets
  channel 2 (reward): enemy fish, enemy submarines and divers
  channel 3 (projectile): the player's bullets
  channel 4 (trail): the cell just behind each enemy and diver, and the submarine's back cell
  channel 5 (gauge): the oxygen bar and the diver bar along the bottom row
THE OUTPUT (6 numbers, logits) for the actions 0 no-op, 1 left, 2 up, 3 right, 4 down, 5 fire; the action is sampled from the softmax of the logits. With probability 0.1 the game repeats the previous action instead (sticky actions).
How the 6 channels are built from the game's own channels (state() in the source): channel 0 (player) <- sub_front, sub_back; channel 1 (danger) <- enemy_fish, enemy_sub, enemy_bullet; channel 2 (reward) <- enemy_fish, enemy_sub, diver; channel 3 (projectile) <- friendly_bullet; channel 4 (trail) <- trail, sub_back; channel 5 (gauge) <- oxygen_guage, diver_guage. A cell is 1 in a channel if any of its source channels is 1.

THE NETWORK (the same architecture as the reinforcement-learning networks it will be compared with): a multilayer perceptron with 600 inputs, two hidden layers of 32 units with tanh activations, and 6 outputs; 20,486 parameters:
  h1 = tanh(x @ W1 + b1)          W1: 600 x 32, b1: 32
  h2 = tanh(h1 @ W2 + b2)         W2: 32 x 32,  b2: 32
  logits = h2 @ W3 + b3           W3: 32 x 6,  b3: 6
Row i of W1 holds the weights from input i to the 32 first-layer units; column j of a weight matrix belongs to unit j of the next layer. EVERY WEIGHT STARTS AT 0; you set the weights you need.

HOW YOUR NETWORK IS SCORED: its mean score per episode over 1,000 episodes, each action sampled from the softmax of the logits (with the sticky actions above); an episode also stops after 10,000 steps. It is compared with networks of the same architecture trained by reinforcement learning on this game.

HOW TO WRITE THE WEIGHTS (numbers only; nothing is run). Write a code block whose opening line is three backticks followed by the word edits, one statement per line ('#' starts a comment; a long list may continue over the next lines). Tensors: W1, b1, W2, b2, W3, b3.

```edits
W1[12, 0] = 2.5                     # one entry: row 12, column 0
W1[0:6, 3] = [1, 0, -1, 0, 2, 0]    # explicit values along a range (as many values as entries)
b1[0:4] = -1                        # fill a range (a:b is half-open; ':' alone = the whole axis)
W1[3:600:60, 0] = [0, 0, 0, 0, 0, 0, 0, 0, 1, 1]   # column 0 of channel 3, rows 0..9 of the grid -> unit 0
W2[0:2, 0:3] = [[1, -1, 0.5], [0, 2, 0]]   # a 2-D list for a 2-D block (here 2 x 3)
W3[:, 2] *= 2                       # scale (also += and -=)
```
Ranges: a:b is half-open, a:b:s takes every s-th index. Input index i = (row * 10 + column) * 6 + channel. Useful strided ranges: all 10 cells of column c in channel ch are rows c*6+ch : 600 : 60 of W1; all 10 cells of row r in channel ch are rows r*60+ch : r*60+60 : 6.
Statements apply in order; a later statement overwrites an earlier one. Only the LAST edits block of your reply is read; a statement that cannot be read is skipped (the others still apply). Values: plain decimal numbers (|v| <= 1e6).

Failed to read global AGENTS.md instructions from `<local-home>/.codex/AGENTS.md`: Operation not permitted (os error 1)

Code Mode is unavailable because code-mode host is disabled. Code mode will fail closed; enable `features.code_mode_host` and install `codex-code-mode-host`.

**Designing network weights**
**Designing fixed-column weights**
**Designing oxygen-gated weights**

**Designing row-specific detectors**
**Allocating row-gating units**
**Balancing row-gating units**

**Refining tanh gate thresholds**
**Tuning graded row gates**
**Evaluating row-targeting options**

**Positioning for enemy rows**
**Choosing x1 firing position**
**Holding x5 facing left**

**Refining hazard detection**
**Balancing hazard units**
**Testing signed direction units**

**Implementing row occupancy gating**
**Designing row hazard gating**
**Allocating current hazard units**

**Refining hazard features**
**Allocating hazard features**

**Deriving hazard aggregates**
**Calibrating hazard logits**

**Tuning danger-aware weights**
**Refining target gating**

**Adjusting directional thresholds**
**Refining target-row fire gating**

**Deriving score weight constraints**
**Deriving pooled score weights**

**Balancing hazard feature budget**
**Tuning hazard penalties**

**Designing row-sensitive hazard units**
**Tuning row-sensitive hazard units**

**Mapping row hazard gates**
**Tuning target-gate weights**

**Tuning fire boost**
**Tuning return threshold**

**Encoding hazard weights**

**Calibrating hazard-gate thresholds**
**Tuning danger-block thresholds**

**Tuning hazard penalty weights**
**Setting oxygen threshold**

**Tuning centering weights**
**Selecting centering weights**

**Refining target-center gating**
**Tuning target gating**

**Tuning reward weights**
**Tuning movement weights**

**Calibrating hazard weights**
**Calibrating up-action bias**

**Finalizing policy weights**
**Checking fire-state weights**

**Firing at left enemies**
**Testing orientation encoding**

**Refining row-based directional gates**
**Reallocating Y for orientation**

**Refining h1 hazard detection**
**Grouping current hazards**

**Refining compact output encoding**
**Verifying center encoding**

**Choosing row-center pair**
**Adjusting h2 unit weights**

**Checking gate behavior**
**Checking sticky surface gates**

**Checking diver descent logic**
**Checking row-6 hazard avoidance**

**Choosing upward movement**
**Deriving edit ranges**

**Assigning reward/danger weights**
**Assigning B-unit weights**

**Encoding W2 weights, biases**

**Checking action scores**

**Selecting the down move**
**Extending hazard checks**

**Refining vertical hazard margin**
**Adding two-row hazard guards**

**Refining hazard lookahead**
**Checking movement hazard scans**

**Evaluating hazard-avoiding moves**

**Preparing W1 range assignments**
**Selecting W1 range syntax**

**Calculating enemy shot timing**
**Selecting rows 7–8**