Sumway, Thanks for your response. (Now I'm going to have that "Toxic Bob" animation stuck in my head for a few hours) It's more of a learning process for me. I figure if I go about it using the Alien Swarm Source, all it really boils down to is essentially modding over their released source code. (The game was made in Steam's source engine and the original creators made the  first version of the game as a mod for Unreal.) Alien swarm is a top down shooter that was made for free and on steam for this purpose, granted it was to make more levels than the original 6 level campaign. This would be a re-texturing of some assets and creating various new monster types, (Hence the suggestion of the list of Hollywood monster.) Going about making the game/mod this way would reduce development time by leaps and bounds as I wouldn't have to worry too much about set up. I'm doing it for me because I think the end product would be fun overall and it would be a game I, myself, would like to play. The bonus is that it would be a constant tongue in cheek joke to what people believe what popular games should be. But I'll keep in mind of the overall laziness that could prevent me from finishing this thing.