What commercial GB & GBC games have unusual or unique features ?

Isometric graphics: Altered Space, Monster Max, Super R.C. Pro-AM, Twouble
Real time Clock: Harvest Moon GB (Japanese version), Harvest Moon GBC (US & Japanese)
Rumble support: Top Gear Pocket
4-Player adapter support: F1-Race, Tennis, Tetris, TetrisAttack, Waverace
SNES/Super Famicon code: Space Invaders (4Mbit version)
Wire-frame 3D games: Battlezone/Super Breakout, Ray Thunder (Japanese), Xekkusu (Japanese)
Filled-surface 3D games: Faceball 2000, Race Drivin'
Non-licensed GB carts: religion carts, Sachen of Taiwan
Totally redesigned carts: GB Camera, Bandai's Fishing Sonar