Here is a list of the changes that I have noticed in Audiosurf 2 updates.

Snapshots are points where I made a backup copy of AS2 and analyzed it. One snapshot might contain more than one update. The timestamps are when my Steam client downloaded the file. Provided update announcement links are for reference only and do not necessarily correspond to a single Steam update or match the true release time.

Snapshot 17 - October ‎06, ‎2014

October 6: Performance, DX11, Puzzle Balance

Skins

Mods

Snapshot 16 - ‎‎September ‎19, ‎2014

September 19: Puzzle Puzzle Joy Joy!

• changed colorsource in the materialcolor type so it can be set to a constant color rather than a string
• added vector3 support to shadersettings in the material type

Skins

• added Profile API

Mods

• added GetPuzzleRowLocations API
• added AddMinimapMarkers API
• added RumbleActiveGamepad API
• added LoadSounds API
• added LateUpdate callback
• added wakeUpWaitingThreads callback
• added OnPuzzleOverfill callback
• TODO

Snapshot 15 - ‎‎June ‎05, ‎2014, ‏‎8:08:57 PM

Skins

• added OverrideTrackColorForDynamicBlockColors API
• added thrusters.material to gameobject type

Snapshot 14 - ‎‎May ‎29, ‎2014, 2:56 PM

Skins

• added pos, pan, tilt, roll, rot to GetTrack API

Snapshot 13 - ‎‎May ‎28, ‎2014, ‏‎5:58:15 PM

Skins

• removed environment from SetScene API

Snapshot 12 - ‎‎May ‎27, ‎2014, ‏‎1:45:38 AM‏‎

May 27: Game of Dethrones Update

• added rotations, worldspaceoffsets to BatchRenderEveryFrame API
• added fif, deepcopy helper functions

Skins

• added intensity argument to Update callback, bringing it from 4 to 5 total arguments
• added GetLogSpectrum API
• added GetQualityLevel4 API
• added UpdateMeshMorphWeights API
• added BuildMaterial API
• added UpdateShaderSettings API
• added GetMillisecondsSinceStartup API
• added material, prefabKeepExistingMaterial, calculateNormals, calculateTangents, submeshesWhenCombining to the gameobject type
• added colorscaler, sizefalloff, minrenderedsize to the thrusters table in gameobject type
• changed prefabName in the gameobject type to treat the name as a Unity resource name if there is no matching prefab
• changed materials in the gameobject type to allow int material ids instead of material types
• changed shader in the material type to try stripping spaces from the name when the lookup for a built-in shader fails
• added meshes, meshcolors, barycentricTangents, splitVertices, recalculateNormalsEveryFrame to BuildMesh API
• added allowfullmaterialoptions, material *, skyScreen_FixedTrackOffset, ignoretrackscale, textureMode, alphafromintensity, texturemirroreddowntrack, texturetracklength, crossSectionShapeList to CreateRail API
• added sizescaler to SetBlockFlashes API
• added maxvisiblecount to SetBlocks API
• added hide, material *, material to chainspans in SetBlocks API
• added material, material *, reflect to colorblocks, greyblocks, powerups in SetBlocks API
• added BuildMesh support to mesh in colorblocks, greyblocks, powerups in SetBlocks API
• removed powerups.shadercolors from SetBlocks API
• added cameraortho, vehicle.reflect to SetPlayer API
• added offset to SetRings API
• added crease_strength, closecam_near, closecam_far, airdebris_particlesize, airdebris_fieldsize, airdebris_layer, widewater to SetScene API
• changed ambientlight in SetScene API to be "=" set rather than "?=" set, added "highway" and "highwayinverted" choices
• added showsun, skyScreen_FixedTrackOffset to SetSkybox API
• added "highway", "highwayinverted" choices to bottomcolor, topcolor in SetWake API
• added offsets to SetWake API
• removed maxair, maxAir, jumpairtime, pos, pan, tilt, roll from GetTrack API
• added funkyrot, antiairtime, trafficstrength, antitrafficstrength to GetTrack API
• added iCeilingHeight, trackOffset, iTrackIntensities properties to skyscreen shaders

Mods

• added SendCommands API
• added HitTraffic API
• added FlashAirDebris API
• added GetTrack API
• added rot, funkyrot, antiairtime, trafficstrength, antitrafficstrength to GetTrack API
• added CreateRail API
• added "highwayscaledfollowmaxjumpheights" choice to colorMode in CreateRail API
• added GetMillisecondsSinceStartup API
• TODO

Snapshot 11 - ‎February ‎21, ‎2014, ‏‎2:52:29 PM

Unannounced. Several internal architectural changes, one of which adds a graphical glitch to puzzle fly-up sprites.

• No apparent script changes.

Snapshot 10 - ‎‎February ‎15, ‎2014, ‏‎12:26:56 PM

February 11: Updated! Now on Radio: _ensnare_ ! (Steam release accidentally delayed)

Skins

• added calculateTangents, submeshesWhenCombining, calculateNormals to BuildMesh API
• added "trackposition" choice to colorMode in CreateRail API
• added skyScreen_TrackOffset to SetSkybox API
• added iTrackColors, iTrackNodes, iNumTrackNodes properties to skyscreen shaders

Snapshot 9 - ‎January ‎15, ‎2014, ‏‎2:17:33 AM

January 15: "manifold" skin posted to the workshop unannounced

Skins

• CreateLight API now returns an integer
• added UpdateLight API
• added skyScreen_TrackOffset to CreateRail API
• added chainspans to SetBlocks API
• added skyscreenlayer to SetSkybox API
• added tracklocation, playerstrafe, currentWakeboarderJumpHeight arguments to Update callback, bringing it from 1 to 4 total arguments
• added _ProjectInverse, _Scale, _TrackLocation, iTrackTex properties to skyscreen shaders

Snapshot 8 - ‎December ‎29, ‎2013, ‏‎3:27:42 AM

December 29: Updated

• No apparent script changes.

Snapshot 7 - December ‎20, ‎2013, ‏‎3:24:09 AM

December 20: New dynamic-background skin now available on Workshop! + holiday music on radio!
December 13: New radio songs and santa skin
December 7: Live in-game scoreboards added!

Skins

• patched security hole
• added skyscreen to SetSkybox API
• BuildMesh API now returns an integer rather than a userdata object
• BuildMesh API now uses Unity's MarkDynamic function on from-scratch and modified meshes.
• added watertint_highway to SetScene API
  

Mods

• OnSkinLoaded callback can now load assets from the mod folder
• added useLivingScoreboardGhosts to GameplaySettings API
• improved ChangeShaderColors command in SendCommand API

Snapshot 6 - December ‎02, ‎2013, ‏‎6:20:40 PM

November 29: Audiosurf 2 Radio! Jack Conte!

• added "blockcolor_*" choice to colorsource in the materialcolor type
• added shadercolors to powerups array in SetBlocks API
  

Mods

• added GetBlockColors API
• added "ChangeShaderColors" param-based command to SendCommand API

Snapshot 5 - November ‎22, ‎2013, ‏‎4:31:13 PM

November 22: Added music search, mod powerups, and album art skins!

Skins

• added GetAlbumArtPalette API
• changed GetIntensity API to return "normalized" intensity instead of raw intensity
• added texturescale, textureoffset to SetSkybox API
• changed SetSkybox API to only allow skysphere texture changes during first run
• changed powerups in SetBlocks to merge over mod-provided settings
  

Mods

• added SetBlockColors API
• added CreateObject API
• added SetBlocks API
• added OnRequestLoadObjects callback
• added blocktype_grey, blocktype_highway, blocktype_highwayinverted to GameplaySettings API

Snapshot 4 - November ‎15, ‎2013, ‏‎4:26:14 PM

November 15: Automatic music finder added!
November 8: Updated with shuffle playlists, recent songs list, and Visualizer mode!
November 2: Updated with skin features
October 28: Updated! Apple lossless now supported
October 25: Updated with new mod options
October 22: Updated: In-game mod/skin management
October 16: Updated: improved UI

• added pan, tilt, roll, intensity to GetTrack API results
• added scales, override_impactpositions, override_velocities, afternodereached_numbernodesrendered, override_velocities_scaledbytrackspeed to BatchRenderEveryFrame API
• added string version of colors to BatchRenderEveryFrame API

Skins

• added rollscaler to SetPlayer API
• changed SetSky API to improve compatibility between SilverLining and skysphere
• added prefabName, meshmorph, meshmorphsmoothspeed, meshmorphtype to gameobject type
• added visible to CreateObject API
• added CreateRepeatedMeshRail API
• added SetPuzzleGraphics API
• added meshmorph, meshmorphsmoothspeed, meshmorphtype, powerups to SetBlocks API
• removed twistmode from SetScene API except for skins embedded in mods
• changed minimap_colormode in SetScene API to use "=" default instead of "?="

Mods

• added ChangeTraffic API
• changed scripts to reload every time a song loads/restarts
• added collectnow_usingmultiplier to SetPuzzle API
• added OnPuzzleBlockAdded callback
• removed functionality to accept data returned by OnTrackCreated callback
• added powerupname to OnTrafficCreated callback results
• added OnRequestTrackReshaping callback
• removed old gamemode system, possibly changing some of the GameplaySettings API defaults
• changed gravity, jumpheightscaler, matchcollectionseconds in GameplaySettings API to use "=" default instead of "?="
• added puzzleblockfallinterval, blockflight_secondstopuzzle to GameplaySettings API
• added "clog", "stuck", "permanent" choices to greyaction in GameplaySettings API
• changed param in SendCommand to go through a set list of commands (SetTransform, Blink, ChangeTrackNodeOffset) rather than sending arbitrary commands to the specified clone's BroadcastMessage function.
• added semicolon, comma, period to GetInput API results

Snapshot 3 - ‎October ‎11, ‎2013, ‏‎8:25:38 PM

October 11: Updated with improved Wakeboard modes!
October 10: Updated with bumping mono tracks
October 9: Updated with Avatars!, Updated with improved intro fly-in

Skins

• added table version of twistmode to SetScene API

Mods

• added railoffset to SetCamera API
• added smoothstrafetowake to GameplaySettings API
• added position, rotation aliases to the transform2 type

Snapshot 2 - October ‎09, ‎2013, ‏‎8:12:43 PM

October 9: Updated with Avatars!, Updated with improved intro fly-in
October 7: Updates to Mods and UI

• added support for arbitrary string/double entries in SetSkinProperties/GetSkinProperties APIs
• Lua math.random is now seeded with the length of the current song.

Skins

• added colorcount to GetSkinProperties API results
  

Mods

• added DoJump API
• added OnTrickStarted, OnTrickCompleted, OnPlayerLanded, OnPlayerJumped callbacks
• added timing, matchtimer, matchtimerthreshold to SetPuzzle API
• added v3offset to OnTrafficCreated callback results