Silent Hill is a survival horror developed and published by Konami in 1999 for original the Playstation. The game was changed a bit from the beta to the final version, for example the “Grey Child” monster went through four design changes before it was finally approved by censors. Originally a faceless, humanoid monster which resembled a nude child, it was deemed too graphic for audiences (particularly in a game which forces the player to kill them). In the PAL release of the game, the Grey Children do not appear at all, instead being replaced by Claw Fingers. [Info from wikipedia]
Some more beta differences can be noticed in the Japanese Trial demo too. Also, a series of beta / unfinished rooms can be “accessed” using a cheat to pass through walls in the final game.
Thanks to MegaLOL for the contribution!