New Levels:

1. Psychlab.

   1. contributed/psychlab/memory_suite_01/explore_goal_locations_extrapolate
   2. contributed/psychlab/memory_suite_01/explore_goal_locations_holdout_extrapolate
   3. contributed/psychlab/memory_suite_01/explore_goal_locations_holdout_interpolate
   4. contributed/psychlab/memory_suite_01/explore_goal_locations_holdout_large
   5. contributed/psychlab/memory_suite_01/explore_goal_locations_holdout_small
   6. contributed/psychlab/memory_suite_01/explore_goal_locations_interpolate
   7. contributed/psychlab/memory_suite_01/explore_goal_locations_train_large
   8. contributed/psychlab/memory_suite_01/explore_goal_locations_train_small

2. Language binding tasks.

   1. contributed/fast_mapping/fast_mapping
   2. contributed/fast_mapping/slow_mapping

New Features:

1. A property system has been added that allows dynamic querying and modifying of environment state. Level scripts can register and consume custom properties.
2. A new Python module, dmenv_module, is provided that exposes the DeepMind dm_env API.

Minor Improvements:

1. Quake console commands can now be issued via a write-only property.
2. New numeric "accumulate" operations for TensorView and the Lua Tensor types: sum, product, sum-of-squares, and dot product of two tensors.

EnvCApi Changes:

1. "Properties" have been added to the EnvCApi. Properties may be queried, set, and enumerated.
2. The new API version is 1.4 (up from 1.3).
3. The EnvCApi function fps is now deprecated; environments should instead use the new property system to communicate this information.

Bug Fixes:

1. Fix observation 'VEL.ROT' to allow non-zero values when combined with pixel observations. Previously, the presence of pixel observations caused the angular velocity information to be lost due to a logic error.

New Levels:

1. Psychlab.

   1. contributed/psychlab/cued_temporal_production
   2. contributed/psychlab/memory_suite_01/arbitrary_visuomotor_mapping_train
   3. contributed/psychlab/memory_suite_01/arbitrary_visuomotor_mapping_holdout_interpolate
   4. contributed/psychlab/memory_suite_01/arbitrary_visuomotor_mapping_holdout_extrapolate
   5. contributed/psychlab/memory_suite_01/change_detection_train
   6. contributed/psychlab/memory_suite_01/change_detection_holdout_interpolate
   7. contributed/psychlab/memory_suite_01/change_detection_holdout_extrapolate
   8. contributed/psychlab/memory_suite_01/continuous_recognition_train
   9. contributed/psychlab/memory_suite_01/continuous_recognition_holdout_interpolate
   10. contributed/psychlab/memory_suite_01/continuous_recognition_holdout_extrapolate
   11. contributed/psychlab/memory_suite_01/what_then_where_train
   12. contributed/psychlab/memory_suite_01/what_then_where_holdout_interpolate
   13. contributed/psychlab/ready_set_go
   14. contributed/psychlab/temporal_bisection
   15. contributed/psychlab/temporal_discrimination
   16. contributed/psychlab/visuospatial_suite/memory_guided_saccade
   17. contributed/psychlab/visuospatial_suite/odd_one_out
   18. contributed/psychlab/visuospatial_suite/pathfinder
   19. contributed/psychlab/visuospatial_suite/pursuit
   20. contributed/psychlab/visuospatial_suite/visual_match
   21. contributed/psychlab/visuospatial_suite/visually_guided_antisaccade
   22. contributed/psychlab/visuospatial_suite/visually_guided_prosaccade

Minor Improvements:

1. The game demo executable can now print observations at each step.

EnvCApi Changes:

1. The meaning of major and minor versions and the resulting notions of stability are clarified. The new API version is 1.3 (up from 1.2).
2. The EnvCApi act function is now deprecated in favour of two finer-grained functions: A call to act should be replaced by a call act_discrete to set discrete actions, followed by an optional call to act_continuous to set continuous actions. (DeepMind Lab does not use continuous actions.)
3. New support for "text actions", which can be set with the new act_text API function. (DeepMind Lab does not use text actions.)

Bug Fixes:

1. Observation 'DEBUG.CAMERA_INTERLEAVED.TOP_DOWN' is now correct for levels dmlab30/explore_object_rewards_{few,many}.

   An error is now raised if there is not enough space to place every possible room (regardless of whether the random generation actually produces a room of excessive size) and if a non-zero number of rooms was requested.

   The affected levels have been updated and will generate layouts similar to before, but the whole maze is offset by 100 units, and object placements will change.

2. Fix top-down camera for language levels.

3. Correct typo in bot Leonis, skill level 1, based on OpenArena's bot code gargoyle_c.c.

4. Tensor scalar operations using arrays now work similar to the way they do with single values.

New Levels:

1. Psychlab.

   1. contributed/psychlab/harlow

Minor Improvements:

1. Improve documentation of how to configure non-hermetic dependencies (Lua, Python, NumPy).
2. Add 'allowHoldOutLevels' setting to allow running of levels that should not be trained on, but held out for evaluation.
3. Add logging library 'common.log', which provides the ability to control which log messages are emitted via the setting 'logLevel'.
4. Update the ioq3 upstream code to the latest state.
5. Lua 5.1 is now downloaded and built from source, and is thus no longer a required local dependency.
6. A minimal version of the "realpath" utility is now bundled with the code, and thus "realpath" is no longer a required local dependency.

Bug Fixes:

1. Prevent missing sounds from causing clients to disconnect.
2. Fix a bug in the call of the theme callback 'placeFloorModels', which had caused an "'index' is missing" error during compilation of text levels with texture sets that use floor models, such as MINESWEEPER, GO, and PACMAN.
3. Fix bug where levels 'keys_doors_medium', 'keys_doors_random' and 'rooms_keys_doors_puzzle' would not accept the common 'logLevel' setting.
4. Expose a 'demofiles' command line flag for the Python random agent, without which the agent was not able to record or play back demos.
5. Fix a memory deallocation order error introduced by an earlier commit.

New Levels:

1. Psychlab.

   1. contributed/psychlab/glass_pattern_detection
   2. contributed/psychlab/landoltC_identification
   3. contributed/psychlab/motion_discrimination{,_easy}
   4. contributed/psychlab/multiple_object_tracking{,_easy}
   5. contributed/psychlab/odd_one_out

Bug Fixes:

1. Let Python level cache set to None mean the same as not setting it at all.
2. Change Python module initialization in Python-3 mode to make PIP packages work in Python 3.

Minor Improvements:

1. Add support for absl::variant to lua::Push and lua::Read.
2. The demo :game has a new flag --start_index to start at an episode index other than 0.
3. Add a console command dm_pickup to pick up an item identified by its id.
4. More Python demos and tests now work with Python 3.
5. Add a shader for rendering decals with transparency.

New Levels:

1. DMLab-30.

   1. contributed/dmlab30/psychlab_arbitrary_visuomotor_mapping
   2. contributed/dmlab30/psychlab_continuous_recognition

2. Psychlab.

   1. contributed/psychlab/arbitrary_visuomotor_mapping
   2. contributed/psychlab/continuous_recognition

New Features:

1. Support for level caching for improved performance in the Python module.
2. Add the ability to spawn pickups dynamically at arbitrary locations.
3. Add implementations to read datasets including Cifar10 and Stimuli.
4. Add the ability to specify custom actions via 'customDiscreteActionSpec' and
   'customDiscreteAction' callbacks.

Bug Fixes:

1. Fix playerId and otherPlayerId out by one errors in 'game_rewards.lua'.
2. Require playerId passed to game:addScore to be one indexed instead of zero
   indexed and allow game:addScore to be used without a playerId.
3. game:renderCustomView now renders the view with top-left as the origin.
   The previous behaviour can be achieved by calling reverse(1) on the returned
   tensor.
4. Fix a bug in image.scale whereby the offset into the data was erroneously
   ignored.
5. Fix a typo in a require statement in visual_search_factory.lua.
6. Fix a few erroneous dependencies on Lua dictionary iteration order.
7. game:AddScore now works even on the final frame of an episode.

Minor Improvements:

1. Moved .map files into assets/maps/src and .bsp files into assets/maps/built.
   Added further pre-built maps, which removes the need for the expensive
   :map_assets build step.
2. Allow game to be rendered with top-left as origin instead of bottom-left.
3. Add 'mixerSeed' setting to change behaviour of all random number generators.
4. Support for BGR_INTERLEAVED and BGRD_INTERLEAVED observation formats.
5. Add a Lua API to load PNGs from file contents.
6. Add 'eyePos' to playerInfo() for a more accurate eye position of player.
   Used in place of player pos + height.
7. Add support for absl::string_view to lua::Push and lua::Read.
8. Allow player model to be overridden via 'playerModel' callback.
9. Add ability to specify custom actions via 'customDiscreteActionSpec' and
   'customDiscreteAction' callbacks.
10. Add game:console command to issue Quake 3 console commands directly.
11. Add clamp to tensor operations.
12. Add new callback api:newClientInfo, allowing each client to intercept
    when players are loading.
13. Skymaze level generation is now restricted to produce only 100000 distinct
    levels. This allows for caching to avoid expensive recompilations.
14. Add cvars 'cg_drawScriptRectanglesAlways' and 'cg_drawScriptTextAlways' to
    enable script rendering when reducedUI or minimalUI is enabled.
15. All pickup types can now choose their movement type separately, and in
    particular, all pickup types can be made static. Two separate table entries
    are now specified for an item, 'typeTag' and 'moveType'.

Deprecated Features:

1. Observation format names RGB_INTERLEAVED and RGBD_INTERLEAVED replace
   RGB_INTERLACED and RGBD_INTERLACED, respectively. The old format names
   are deprecated and will be removed in a future release.
2. The pickup item's tag member is now called moveType. The old name is
   deprecated and will be removed in a future release.

New Levels:

1. DMLab-30.

   1. contributed/dmlab30/rooms_collect_good_objects_{test,train}
   2. contributed/dmlab30/rooms_exploit_deferred_effects_{test,train}
   3. contributed/dmlab30/rooms_select_nonmatching_object
   4. contributed/dmlab30/rooms_watermaze
   5. contributed/dmlab30/rooms_keys_doors_puzzle
   6. contributed/dmlab30/language_select_described_object
   7. contributed/dmlab30/language_select_located_object
   8. contributed/dmlab30/language_execute_random_task
   9. contributed/dmlab30/language_answer_quantitative_question
   10. contributed/dmlab30/lasertag_one_opponent_small
   11. contributed/dmlab30/lasertag_three_opponents_small
   12. contributed/dmlab30/lasertag_one_opponent_large
   13. contributed/dmlab30/lasertag_three_opponents_large
   14. contributed/dmlab30/natlab_fixed_large_map
   15. contributed/dmlab30/natlab_varying_map_regrowth
   16. contributed/dmlab30/natlab_varying_map_randomized
   17. contributed/dmlab30/skymaze_irreversible_path_hard
   18. contributed/dmlab30/skymaze_irreversible_path_varied
   19. contributed/dmlab30/psychlab_sequential_comparison
   20. contributed/dmlab30/psychlab_visual_search
   21. contributed/dmlab30/explore_object_locations_small
   22. contributed/dmlab30/explore_object_locations_large
   23. contributed/dmlab30/explore_obstructed_goals_small
   24. contributed/dmlab30/explore_obstructed_goals_large
   25. contributed/dmlab30/explore_goal_locations_small
   26. contributed/dmlab30/explore_goal_locations_large
   27. contributed/dmlab30/explore_object_rewards_few
   28. contributed/dmlab30/explore_object_rewards_many

New Features:

1. Basic support for demo recording and playback.

Minor Improvements:

1. Add a mechanism to build DeepMind Lab as a PIP package.
2. Extend basic testing to all levels under game_scripts/levels.
3. Add settings minimalUI and reducedUI to avoid rendering parts of the HUD.
4. Add teleported flag to game:playerInfo() to tell whether a player has teleported that frame.
5. Add Lua functions countEntities and countVariations to the maze generation API to count the number of occurrences of a specific entity or variation, respectively

Bug Fixes:

1. Fix out-of-bounds access in Lua 'image' library.
2. Fix off-by-one error in renderergl1 grid mesh rendering.

New Levels:

1. Psychlab, a platform for implementing classical experimental paradigms from
   cognitive psychology.

   1. contributed/psychlab/sequential_comparison
   2. contributed/psychlab/visual_search

New Features:

1. Extend functionality of the built-in tensor Lua library.
2. Add built-in image Lua library for loading and scaling PNGs.
3. Add error handling to the env_c_api (version 1.1).
4. Add ability to create events from Lua scripts.
5. Add ability to retrieve game entity from Lua scripts.
6. Add ability create pickup models during level load.
7. Add ability to update textures from script after the level has loaded.
8. Add Lua customisable themes. Note: This change renames helpers in
   maze_generation to be in lowerCamelCase (e.g. MazeGeneration ->
   mazeGeneration).
9. The directory game_scripts has moved out of the assets directory, and
   level scripts now live separately from the library code in the levels
   subdirectory.

Minor Improvements:

1. Remove unnecessary dependency of map assets on Lua scripts, preventing
   time-consuming rebuilding of maps when scripts are modified.
2. Add ability to disable bobbing of reward and goal pickups.
3. The setting controls (with values internal, external) has been renamed
   to nativeApp (with values true, false, respectively). When set to
   true, programs linked against game_lib_sdl will use the native SDL input
   devices.
4. Change LuaSnippetEmitter methods to use table call conventions.
5. Add config variable for monochromatic lightmaps ('r_monolightmaps'). Enabled
   by default.
6. Add config variable to limit texture size ('r_textureMaxSize').
7. api:modifyTexture must now return whether the texture was modified.
8. Add ability to adjust rewards.
9. Add ability to raycast between different points on the map.
10. Add ability to test whether a view vector is within an angle range within a
    oriented view frame.

Bug Fixes:

1. Increase current score storage from short to long.
2. Fix ramp jump velocity in level lt_space_bounce_hard.
3. Fix Lua function 'addScore' from module 'dmlab.system.game' to allow
   negative scores added to a player.
4. Remove some undefined behaviour in the engine.
5. Reduce inaccuracies related to angle conversion and normalization.
6. Behavior of team spawn points now matches that of player spawn points.
   'randomAngleRange' spawnVar must be set to 0 to match previous behavior.

This is the initial public release of DeepMind Lab.