| Cool Boarders Burrrn (Jun 22, 1999 prototype) | 22 June 1999 19:57:34 | Dreamcast | Sports - Snowboarding | - |
| Cool Cool Jam (Demo) | | Neo Geo Pocket Color | Rhythm | - |
| Cool Spot (European build) | | Sega Mega Drive | Platform | - |
| Cool Spot (Mega Drive prototype) | | Sega Mega Drive | Platform | - |
| Cooly Skunk (Prototype) | | SNES | Action | ✓ |
| Corn Buster (Prototype) | | SNES | Action | ✓ |
| Corpse Party: Book of Shadows (JP demo) | | PlayStation Portable | Adventure | - |
| Corpse Party: Sweet Sachiko’s Hysteric Birthday Bash (Trial demo) | | PlayStation Portable | Adventure | - |
| Corridor 8 (prototype) | | PC | | ✓ |
| Corvette (Aug 4, 2003 prototype) | 4 August 2003 21:01:08 | Xbox | Racing | - |
| Cosmic Carnage (Oct 11, 1994 prototype) | 11 October 1994 06:32:32 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Oct 13, 1994 prototype) | 13 October 1994 06:42:58 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Oct 4, 1994 prototype) | 4 October 1994 09:43:02 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Oct 5, 1994 prototype) | 5 October 1994 09:17:16 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Oct 7, 1994 prototype) | 7 October 1994 09:40:00 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Sep 21, 1994 prototype) | 26 September 1994 06:41:50 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Sep 26, 1994 prototype) | 27 September 1994 19:41:46 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Sep 28, 1994 prototype) | 3 October 1994 08:39:24 | Sega 32X | Fighter (2D) | - |
| Cosmic Carnage (Sep 6, 1994 prototype) | 6 September 1994 14:24:30 | Sega 32X | Fighter (2D) | - |
| Cosmic Swarm (prototype) | | Atari 2600 | Fixed Shooter | - |
| Cosmo Tank (US Prototype) | | Game Boy | Action | - |
| Cosmos Chaos (prototype) | | Nintendo DS | Edutainment | - |
| Costume Quest (Aug 22, 2010 prototype) | 22 August 2010 | Xbox 360 | Action & Adventure | - |
| Countdown Vampires (Feb 15, 2000 prototype) | 15 February 2000 13:14:48 | PlayStation | Survival Horror | - |
| Counter-Strike (Oct 22, 2003 prototype) | 22 October 2003 | Xbox | First-Person Shooter | - |
| Counter-Strike (Sep 5, 2003 prototype) | 5 September 2003 02:52:45 | Xbox | First-Person Shooter | - |
| Counter-Strike: Condition Zero (Sep 24, 2003 prototype) | 24 September 2003 | PC | Shooter | - |
| Counter-Strike: Global Offensive (Aug 8, 2011 prototype) | 8 August 2011 | PC | First-Person Shooter | - |
| Counter-Strike: Global Offensive (Feb 24, 2012 prototype) | 24 February 2012 | PC | | - |
| Counter-Strike: Global Offensive (Jun 7, 2012 prototype) | 7 June 2012 | Xbox 360 | First Person-Shooter | - |
| Counter-Strike: Global Offensive (Mar 16, 2012 prototype) | | PC | | - |
| Counter-Strike: Global Offensive (Mar 9, 2012 prototype) | | PC | | - |
| Counter-Strike: Global Offensive (Nov 29, 2011 prototype) | 29 November 2011 | PC | First-Person Shooter | - |
| Crack'ed (Nov 28, 1988 prototype) | | Atari 2600 | | ✓ |
| Crackdown (Apr 3, 2006 prototype) | 3 April 2006 00:00:00 | Xbox 360 | Action Adventure | - |
| Crackdown (Apr 30, 2007 prototype) | 30 April 2007 07:17:43 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 21, 2006 prototype) | 21 March 2006 03:21:09 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 22, 2006 prototype) | 22 March 2006 03:08:06 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 3, 2006 17.09 prototype) | 3 March 2006 17:09:02 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 3, 2006 prototype) | 3 March 2006 16:38:16 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 30, 2007 prototype) | 30 March 2007 10:36:40 | Xbox 360 | Action Adventure | - |
| Crackdown (Mar 7, 2006 prototype) | 7 March 2006 11:45:30 | Xbox 360 | Action Adventure | - |
| Crackdown (Sep 1, 2005 prototype) | 1 September 2005 00:00:00 | Xbox 360 | Action Adventure | - |
| Crank the Weasel (Prototype) | 2002 | PC | Action | ✓ |
| Crash 'n' Burn (Aug 23, 2004 prototype) | 23 August 2004 | PlayStation 2 | Racing, vehicular combat | - |
| Crash 'n' Burn (Aug 25, 2004 prototype) | 25 August 2004 | PlayStation 2 | Racing, vehicular combat | - |
| Crash 'n' Burn (Aug 31, 2004 prototype) | 31 August 2004 14:26:36 | Xbox | Racing | - |
| Crash Bandicoot (Apr 8, 1996 prototype) | 8 April 1996 | PlayStation | Platform | - |
| Crash Bandicoot (Jul 15, 1996 prototype) | 15 July 1996 22:43:04 | PlayStation | Platform | - |
| Crash Bandicoot (May 11, 1996 prototype) | 11 May 1996 | PlayStation | Platform | - |