Well, if you liked it, be sure to check back and comment on the custom levels that I'll continue to post up here.
The feedback will help me know what levels are too hard or too easy and which are fun, as well as finding out if someone who doesn't know how the level was put together will be able to figure out the level or a way around the intended method of winning.
Also the more people that get hooked into this game, the more people there will be who might get play around with the level editor and pull up some more nice custom levels to work with. I'm on my 15th level now, but there could be hundreds of levels for this if we got some more people working on it.
BTW, you did beat the 21st level as well, right? If you beat the game and got to the ending credits then you would have played through 21 levels.
Currently wrapped up in: Half Life, Portal, and User Created Source Mods