Don't worry, Doom can not compare with Metroid because the two games are just so different. In Metroid there are weapons that are infinite in their ammo supply, and those that are finite are easily restocked. And while the baddies in Metroid are tough they're not impossible. Just gotta know -how- to take them down.

Also, in many parts of the game there are puzzles to solve before you can move on. This is usually walls that can only be broken down in certain ways or areas you can't enter without certain upgrades. Sometimes you can easily enter an area, the problem is just finding the way through. And good god there are some upgrades that are hard as hell to get at.

So while Doom is all about how big your gun is and the grossout factor, Metroid has always been about fast paced strategy and problem solving and the woman you play as. ^_^

-NeoRaven
I'd still like to see Samus in the UF.