Altitude is a 2d multiplayer game, released in 2009 by Nimbly Games.

This repository is my ongoing attempt to make Altitude a nice environment for reinforcement learning in my (super limited) free time.

So far, we have:

• A simple protobuf message format that can stream game state at around 12 kbps (raw) or 3 kbps (gzipped). (See proto/ and the section below for details.) Once gzipped, this is roughly as efficient (by maybe a factor of two) as the netcode used by the game but at least 80% less arcane. (Most importantly, it doesn't require the reader to simulate any parts of the game or keep track of any state besides perhaps object IDs).
• Hooks in the game engine to stream game state using the new message format. (The source for Altitude is not yet publically available, so these changes are not available in this repository.)
• An in-browser replay viewer for "recordings"---gzipped streams of game state (extension .pb.gz), and an indexer utility to load directories of saved replays into an sqlite database so you can find the ones you want. See the site_gen target.

proto/ contains the message format used to serialize game state, game inputs, and geometry of game objects.

I've patched Altitude itself (not fully open source) to serialize game state to a stream of Update messages. An Update is roughly a screenshot of all game-relevant state at a given moment in time besides map geometry. This ncludes information not normally available to a player like positions of off-screen planes, powerups held by enemies, and exact health/energy values of all planes.

A replay (extension .pb.gz) is just a gzipped sequence of length-delimited Update messages.

The bandwidth of a game with 8 players (like 4v4 ball) tends to be about 0.2 megabytes per minute after gzipping, or roughly 100x less than the bandwidth of 720p video.

Map geometry is sent in the first Update message when a game begins. Besides map geometry, the only additional information needed to interpret an Update are the relative hitboxes of game objects like planes and projectiles. out/polys is a gzipped sequence of length-delimited Poly messages (as defined in proto/poly.proto) giving the hixboxes of different game objects. This data is read from poly_src, an bunch of XML files copied from Altitude.

Planes have different hitboxes depending on their "roll." The degrees of roll for which hitboxes are available are irregularly distributed.

hx_src/ contains a few tools and the replay viewer.

Haxe source for a replay viewer using the Heaps game engine.

Source files for a static website that acts as a replay browser and viewer. (Work in progress.)

Build static webpages where you can view replays. Host with server.sh.

Copy the generated Java source for our protobuf messages into the Altitude source repository located at ALTI_PATH.

Copy the last recorded game to example_recordings/$1.pb.gz. (First set RECORDING_PATH to your Altitude instalation directory.)

Build the indexer with make indexer/ and run indexer/Indexer $RECORDING_DIR to build an sqlite database with information on all the replays in $RECORDING_DIR.

Currently indexes:

• Maps and durations of games
• Active players in games and how long they played
• Goals
• Messages