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Overview

DOOM Neuron supports multiple game scenarios with different difficulty levels and training objectives. The scenario is configured via TrainingConfig.doom_config in code (not a CLI argument).
The default scenario is progressive_deathmatch.cfg, which is recommended for most training runs.

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Available Scenarios

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Progressive Deathmatch (Default)

Config: progressive_deathmatch.cfg
WAD: progressive_deathmatch.wad 
PPOConfig.doom_config = "progressive_deathmatch.cfg"
Similar to survival mode but with enhanced gameplay mechanics:
  • Ammo Management: Kills don’t reset ammo count, encouraging proper ammo conservation
  • Movement Tweaks: Modified movement mechanics make training easier
  • Progressive Difficulty: Difficulty scales as agent improves
Best for:
  • Default training runs
  • Learning ammo management strategies
  • Agents that need to balance aggression with resource management
This is the recommended scenario for most users. It provides the best balance of challenge and trainability.

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Survival

Config: survival.cfg
WAD: survival.wad 
PPOConfig.doom_config = "survival.cfg"
Classic survival scenario:
  • Objective: Survive as long as possible against waves of enemies
  • Ammo Reset: Kills reset ammo count (unlimited ammo when killing)
  • Difficulty: Moderate, good for testing basic combat skills
Best for:
  • Testing combat abilities without resource management
  • Agents focused on survival and kill count
  • Baseline comparisons

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Deadly Corridor Curriculum

Configs: deadly_corridor_1.cfg through deadly_corridor_5.cfg
WAD: deadly_corridor.wad A progressive curriculum with 5 difficulty stages:
1

Stage 1: deadly_corridor_1.cfg

Easiest stage - Introduction to corridor navigation
PPOConfig.doom_config = "deadly_corridor_1.cfg"
  • Minimal enemies
  • Focus on basic movement
  • Learn corridor geometry
2

Stage 2: deadly_corridor_2.cfg

Beginner stage - Adding combat elements
PPOConfig.doom_config = "deadly_corridor_2.cfg"
  • More enemies introduced
  • Basic combat required
  • Movement still forgiving
3

Stage 3: deadly_corridor_3.cfg

Intermediate stage - Balanced challenge
PPOConfig.doom_config = "deadly_corridor_3.cfg"
  • Moderate enemy density
  • Requires movement + combat coordination
  • Armor pickups become important
4

Stage 4: deadly_corridor_4.cfg

Advanced stage - High difficulty
PPOConfig.doom_config = "deadly_corridor_4.cfg"
  • High enemy density
  • Strategic positioning required
  • Resource management critical
5

Stage 5: deadly_corridor_5.cfg

Benchmark stage - Significant difficulty jump
PPOConfig.doom_config = "deadly_corridor_5.cfg"
  • This is the official benchmark
  • Massive difficulty increase from stage 4
  • Requires refined strategies
  • Agents trained on 1-4 may develop suboptimal habits (e.g., running straight for armor)
Deadly Corridor Curriculum Notes:
  • Stages 1-4 ramp difficulty gradually
  • Stage 5 is a significant jump and is the actual benchmark
  • Training through 1-4 may result in movement habits that underperform on stage 5
  • Consider fine-tuning on stage 5 with a lower learning rate to adapt behavior

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Curriculum Strategy

For deadly corridor training, use this recommended progression:
Train sequentially through stages 1-4, then fine-tune on stage 5:
# Stage 1 - Initial training
python3 ppo_doom.py  # with doom_config="deadly_corridor_1.cfg"

# Stage 2 - Load checkpoint from stage 1
python3 ppo_doom.py  # with doom_config="deadly_corridor_2.cfg"

# Stage 3 - Load checkpoint from stage 2
python3 ppo_doom.py  # with doom_config="deadly_corridor_3.cfg"

# Stage 4 - Load checkpoint from stage 3
python3 ppo_doom.py  # with doom_config="deadly_corridor_4.cfg"

# Stage 5 - Fine-tune with LOWER learning rate
python3 ppo_doom.py  # with doom_config="deadly_corridor_5.cfg", learning_rate=1e-4

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Scenario-Specific Tuning

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Progressive Deathmatch & Survival

Default PPO parameters work well: 
PPOConfig(
    doom_config="progressive_deathmatch.cfg",
    learning_rate=3e-4,
    gamma=0.99,
    gae_lambda=0.95,
    steps_per_update=2048,
    batch_size=256,
    num_epochs=4
)

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Deadly Corridor

Tuned parameters from testing (reference values): 
PPOConfig(
    doom_config="deadly_corridor_5.cfg",
    
    # Ray-cast features tuned for corridor geometry
    wall_ray_count=12,
    wall_ray_max_range=64,
    wall_depth_max_distance=18.0,
    
    # Encoder configuration
    encoder_trainable=True,
    encoder_entropy_coef=-0.10,  # Encourage confident stimulation
    encoder_use_cnn=True,
    encoder_cnn_channels=16,
    encoder_cnn_downsample=4,
    
    # Decoder configuration
    decoder_zero_bias=True,  # Prevent decoder-sided learning
    decoder_enforce_nonnegative=False,
    decoder_freeze_weights=False,
    decoder_use_mlp=False,  # Linear decoder for transparency
    
    # Distance normalization for deadly corridor geometry
    enemy_distance_normalization=1312.0,
    
    # Feedback settings
    use_reward_feedback=True,
    feedback_positive_amplitude=2.0,
    feedback_negative_amplitude=2.0
)
The values above are tuned specifically for deadly corridor scenarios. Other scenarios (progressive deathmatch, survival) will likely require different values for:
  • Feedback scaling
  • Reward shaping
  • Ray-cast geometry
  • Curriculum pacing
Treat these as a starting point only.

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Screen Resolution

All scenarios use RES_320X240 by default: 
PPOConfig(
    screen_resolution="RES_320X240",  # 320x240 resolution
    encoder_use_cnn=True               # CNN processes screen buffer
)
Higher resolutions require adjusting CNN parameters: 
PPOConfig(
    screen_resolution="RES_640X480",
    encoder_cnn_channels=32,      # Bump channels for higher resolution
    encoder_cnn_downsample=8      # Adjust downsampling
)

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Action Spaces

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Hybrid Actions (Default)

Continuous + discrete actions for high movement fidelity: 
PPOConfig(
    use_discrete_action_set=False  # Hybrid actions (default)
)
Provides:
  • Smooth movement
  • Precise aiming
  • Better visual appeal
  • Higher entropy (requires more training)

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Discrete Actions

Simplified action space for faster convergence: 
PPOConfig(
    use_discrete_action_set=True  # Discrete-only actions
)
Provides:
  • Lower entropy
  • Faster training
  • Reduced movement fidelity
  • Less visually impressive
Only use discrete actions if hybrid actions fail to converge after extensive tuning. The movement quality is significantly reduced.

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Monitoring Training

Track scenario-specific metrics with TensorBoard: 
tensorboard --logdir checkpoints/l5_2048_rand/logs --port 6006
Key metrics to watch:
  • episode_reward - Total reward per episode
  • episode_length - Survival time
  • kill_count - Enemies eliminated
  • policy_loss - PPO policy gradient loss
  • value_loss - Value function error

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Next Steps

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