This is shameful.
Saying you were "inspired" by something doesn't take away from the fact that you are ripping off the work of indy game developers and doing nothing to change it. Don't even try to compare this to having more than one FPS. Yes there are more than one tower defense games but not all of them are ripoffs of one particular one.
Quake and halo are different from doom in too many ways to list. This is just the exact same game and mechanics with different sprites. You are a vulture. It's bad enough that you are taking customers away from a game company that deserves recognition for a great ORIGINAL game but if you start putting in ads to make money of this, you are a thief. Just saying, I have seen that before on this site. Make something original and have some ads, perfectly fine. Rip someone else off and you are not making a tribute, you are a game design vulture and nothing more.
As for the game itself, not bad. I liked it....also liked it the first time I played it when it was called plants vs zombies.