I have started a micro ISV. I’m writing some software aimed at casual game developers who use Flash. The Flash space is pretty complicated: There have been ten major versions of the Flash player over more than a decade. There are two major languages for writing Flash games: ActionScript 1-2 and ActionScript 3. Each language lets you use a different, overlapping set of features. You can author Flash files with graphical design tools or open-source command-line compilers. I need to figure out which uses of Flash I will support in “version one” of the software I’m writing.

I have decided to tackle the problem of deciding what to support by measuring what developers actually use: I played 123 SWF files that were linked from the front page of a popular Flash game site. Popular games and recent games appear on the front page of this site, which means these data are biased towards popular games and recent games. That’s OK—the software I’m writing is for successful, active Flash game developers. They should be the ones writing popular, recent games.

80% of the games are Flash version 9 or 10. Despite that only 73% (but still 73%) of the games use ActionScript 3.

Forty-eight different kinds of tags appear. Here’s a histogram the number of games which use each kind of tag (not the number of times the tag appears):

123 ShowFrame
123 End
122 SetBackgroundColor
119 FileAttributes
119 DefineSprite
109 DefineShape3
108 DefineShape2
 96 FrameLabel
 90 SymbolClass
 89 DefineBitsLossless2
 87 DoABC
 73 ScriptLimits
 64 DefineBinaryData
 59 DefineSound
 59 DefineShape
 55 DefineFontAlignZones
 55 DefineFont3
 53 DefineEditText
 52 DefineBitsJPEG2
 51 DefineText
 51 DefineShape4
 50 SoundStreamHead2
 49 CSMTextSettings
 48 PlaceObject2

 47 DefineFontName
 46 RemoveObject2
 43 DefineBitsJPEG3
 42 DefineButton2
 41 ExportAssets
 33 DoInitAction
 33 DoAction
 32 UnrecognizedTag
 31 DefineMorphShape
 30 JPEGTables
 30 DefineBits
 28 PlaceObject3
 19 DefineSceneAndFrameLabelData
 19 DefineBitsLossless
 18 DefineMorphShape2
 17 Protect
 14 Metadata
 13 DefineText2
  8 StartSound
  8 EnableDebugger2
  8 DefineScalingGrid
  7 DefineVideoStream
  7 DefineFont2
  5 DefineButtonSound

OK, everyone uses ShowFrame and End, no surprises there. Thirty-two files had tags which aren’t mentioned in the SWF file format spec. Here are the offending tag numbers, the number of files they appeared in, and the number of times they appeared:

Tag  # Files  # Times
253       9      536
255      16       16
 41      11       11
 63       6        6
 72       3        3

If you know what tags 41, 63, 72, 253 and 255 mean please post a comment!

Lastly, here’s how popular different combinations of file attributes are:

 69 ActionScript3 UseNetwork
 16 (FileAttributes tag present; nothing turned on)
 11 UseNetwork
 10 HasMetadata ActionScript3 UseNetwork
  9 ActionScript3
  2 HasMetadata ActionScript3
  1 UseGPU
  1 HasMetadata

These data are from games on one site, so I’m not going to make any firm decisions about what the software I’m writing will support just yet, but it looks like:

• Because I only have resources to support one of ActionScript 1-2 or ActionScript 3 at first, it would be better to support ActionScript 3.
• These games use 48 different kinds of tags I need to understand. (Incidentally, concentrating on ActionScript 3 doesn’t simplify things—the ActionScript 3 games use 45 different kinds of tags between them.)
• A lot of games want to use the network. There’s no easy way to tell if they work unplugged from the network too, though.

Next I need to pull apart the contents of the DoABC tags and see how much of the Flash API these games use. I also need to look at games from other popular Flash game sites.