Interception

Interception is a vanilla-compatible megawad for DOOM II. In the far distant future, you are part of a team of marines who are sent a distress signal from an archaeology site. Once you arrive, the rest of your team is killed by some nasty hell spawns. Now it's your job to stop the invasion, or die trying. Along the way, you explore ancient military bases, an underground necropolis, and Hell itself.