On top of the seven included games (plus the two secret ones), there are four more older games hidden away as raw SWF files in the steamapps/common/basement/moregames folder. These are:

• Clubby The Seal (2004)
• Viviparous Dumpling (2005)
• Carious Welting (2003)
• Carious Welting 2 (2005).

Unlike the other games in the collection, these are unaltered from their original Newgrounds release.
Contributed by DeerBoarDude