I wasn't aware this game had any DLC. Might have to give it another go
I wasn't either in terms of achievements. Auto popped a bunch just booting it up after playing the base quite a bit.
Game has so much added to what I remember on release. Bit overwhelming :D
Complete 7 Daily Missions - Embr
Protect humanity's treasures from invaders with no taste. - Serious Sam 4
Discover Fulbert's great invention. - Serious Sam 4