Could someone tell me what game mode I'm thinking of?

There was a game mode I played long ago in which you got kills for cash which you could spend on guns, buying them temporily for a small amount of money or permanently for alot. You could make makeshift bases using a type of “fading door.” You could also make ammo crates and spawn points, and it was a simple deatchmatch though you could team up with people.

Stronghold.

I love you.