Blade Rush was added in January, but it is rated above 8, has nearly 500,000 plays, and includes achievements, some of which could be turned into quests if the developer could be contacted.
Crunch Squash an enemy with another
Thunk Take out 2 enemies in one rush
Stealth Take out all enemies without any alerts
Ghost Take out all enemies completely unseen
Murderator Kill 3 enemies within 3 seconds
Blistering Beat a level in under 10 seconds
What ground? Rush 4 enemies while airborne
Hang Time Stay in the air for 6 seconds
No Evidence Drop all enemies outside the stage
Tempt Fate Trigger 20 traps in a single level
Up Up... Get maximum altitude above the screen
Bullet Time Dodge 3 gunshots
Taken directly from the achievements page in the game.
