Here is the alpha version of blood, it doesent really seem all that different from the finished game, the pitchfork shoots fireballs for some reason, the tnt is alot thinner, different music, etc. Whats interesting though is that one of the alpha maps was recycled for the plasma pack expansion.

The biggest difference though is the desighn of caleb. He looks like a cultist in this alpha, thank god they did not stick with this desighn for him.

http://www.youtube.com/watch?v=FubEc7FAMes - alpha map 01

http://www.youtube.com/watch?v=XCoCcUiUdHs&feature=related - alpha map 02

http://www.youtube.com/watch?v=BzC3trGve2A&feature=related - third person view video

Great find! I always loved similar things, it gives a lot of insight into development of a game.

There is a partial source code for that thing floating on a web :).

That's for the developers. Similar to the original reason for cheat codes existing in games in the past. They originally planned two sets of TNT for the full game, a single TNT stick and a TNT bundle. Likely removed because it would have been too excessive. Quite a lot of it was still used in the early betas and even the shareware releases. Many would agree that the decision to replace them with more atmospheric music was the right choice. Well he was part of the Cabal, it was an interesting design choice at the time.