Game versions

Official version
You can get one only if you donated on Humble Mojam Bundle (or on PirateBay, with official permission from Mojang). Contains major bugs like Harvester crash, broken scoring (second player gets your points) and Multiplayer lags. Probably all of them were intended to force community to get source and fix/modify/mess with it. Still, thank you, Mojang for coding such addictive game.

Fixed vanilla version
It was right there, on forums, in Download forum. No idea where it is now. If anybody finds it, post it there.

It contains vital bug fixes for the original game, everything else has been left untouched.

Uber Catacomb Snatch
Can be found at UberCS.com:

Watch a review of the old 1.3 video review at http://www.youtube.com/watch?v=kfem2eOh1X8

Contains major bug fixes for the official version and includes many new features like:
 * Harvesters display how much coin they are carrying and Rail Droids can pick up coin from them.
 * Localization allowing other languages. (Currently only has a file for English to get others you need to edit the English one or inject new files)
 * Added animated how to play screen that is integrated into the localization system. For new players this is a very nice feature.
 * Rail Droids have a more advanced behavior (This allows much more complex routes thus allowing many more droids.)
 * Overhauled the GUI system.
 * A more steam-punk feel to the menus (although not all the way there yet in my opinion. But still better then others out there.)
 * GUI based key binding. As well as advanced keybinding if you edit a file.
 * Improved controls
 * Options screen
 * Mute Music or All sounds.
 * show/hide FPS that is displayed in the corner.
 * Can toggle Movement Locking while shooting.
 * Fixed a bug that made the player shoot through a sarcophagus when right up next to it along with some walls.
 * Ability to load custom maps.
 * Shows internal and external IP when hosting.

Maescool's repository version
Contains major bug fixes for the official version and includes many new features like: Can be found here.
 * mouse aim
 * map loader and new maps
 * reskinned buttons and destructible walls
 * info messages
 * 4 difficulty levels
 * fullscreen
 * options menu
 * exp, levels for player and buildings
 * instructions how to play
 * shows your external IP when you are host