I have many windows games on my PC like Doom, Doom 2, Diablo, Diablo 2, Diablo 3, NFS Games, Left 4 Dead games call of Duty games, Halo games and many many more games i have in my Laptop. I just like to know if its possible to intall them and play them on Ubuntu without using Steam, im not a Steam fan at all. Because im a Hard core gamer and i dont want to change from Window 8.1 to Ubuntu if all of my games are not compatible.
Most of those games do not have Linux native versions, but many work well using Wine. You can find out more about which games work in Wine and how well using the app database:
Doom, in particular, has lots of Linux ports and can be played natively.
Most of the games work in Ubuntu under wine. Wine is program that let's you run windows programs on Linux(ubuntu) without emulation(no CPU loss, lagging, etc.). You can check if certain game(or program) is compatible with wine and if it possibly has some problems running on wine on Wine HQ. Just enter the game you want in search. I'll do it for the games you mentioned, but you can see more details by clicking on the links.