Newbie here, who is actually familiar with the Sega CD. I've rebuilt a few and currently own a CD-X, X'Eye, 1st gen with a Sony drive, 2nd gen with a JVC drive, and another 2nd gen with a Sharp drive. Want to get my hands on a Pioneer LaserActive.

Anyways, my picks (much more than 20):

Lunar: The Silver Star (Working Designs, Game Arts)

Lunar: Eternal Blue (Working Designs, Game Arts)

Vay (Working Designs, Sims)

Popful Mail (Working Designs, Falcom, Sega)

Keio: Flying Squadron (JVC)

Snatcher (Konami)

Shining Force CD (Sega)

Dark Wizard (Sega)

Heart of the Alien: Out of this World, Parts 1 and 2 (Only Sega CD version has the sequel to the first OOTW) (Virgin, Interplay, Delphine)

Prince of Persia (Sega CD version is unique with different levels in comparison to the original) (JVC, Broderbund)

Road Avenger (Renovation, Data East)

Time Gal (Renovation, Taito)

The original "Night Trap" (Sega, Hasbro, Digital Pictures)

Robo Aleste (Tengen "Atari", Sega, Compile)

Silpheed (Sega, Game Arts)

Sonic CD (Sega)

The Third World War (Extreme, Micronet)

The Adventures of Willy Beamish (Sierra "parent company of Dynamix")

The Rise of the Dragon (Sierra "parent company of Dynamix")

Panic! (Sega, Data East)

Mickey Mania! (Sega CD version is the best) (Sony, Disney, Traveler's Tales)

Road Rash (Electronic Arts)

The Secret of Monkey Island (JVC, LucasArts)

AH-3 Thunderstrike (JVC)

Revenge of the Ninja (Renovation, Taito)

Pugsy (Psygnosis)

The Amazing Spiderman vs. the Kingpin (Sega)

Batman Returns (Sega)

Final Fight CD (Sega, Capcom)

Android Assault: The Revenge of Bari-Arm (Sega, Human, Big Fun Games)

Wing Commander (full speech, different music, graphically most faithful to original) (Electronic Arts "parent company of Origin Systems")

- Reinhart