To clear some things up, it's been almost 9 years since the game came out in 2001, and since Monolith shut down the online servers and the fan support died out, I was only left to play single-player. Therefore, the sweet memories of inter-species multiplayer is going to stay as memories, and nothing else.
Marine Campaign

The Marines campaign has you playing as Corporal Harrison of the Colonial Marines. After losing contact with a research facility, the Colonial Marines are sent to investigate. After a failed landing, the tutorial mission tasks you with turning on the power to a landing pad so the ship can land properly. The game creates the most forced situations possible, in order for you to progress through the level alone. While it does definitely build tension, it's not the first time you walk into a building and have the entrance collapse, and hearing your squadmates say "well, do it yourself, we can't do anything about it."
Throughout the first level, it's a buildup, not knowing if an Alien could be lurking around the next corner. It's a dark place, and definitely atmospheric even today. For the first half of the mission, it's meant to scare you, with motion tracker blips, areas stained with blood, etc. However, you don't fight a single enemy, until you complete the objective by restoring power. Throughout this mission, the lack of enemies is terrifying. Then after completing the objective, you then awaken the Aliens and that's when things go downhill.
The gunplay reeks of generic style. The combat is not very engaging and feels stale. This definitely hasn't aged well, but I can see how this was awesome at the beginning of the 21st century. Since you're always anticipating an enemy around the next corner, and it's supposed to be a scare tactic, is it just pointless if the combat is not fun?
The scare factor is also greatly dumbed down with the "save anywhere" save system, meaning as long as you can pause the game at any point in time, you can also save the game. It kills all tension you have because there's no worries with this kind of save method.
Basically, the campaign consists of atmospheric environments and monster closets full of dry, unsatisfying combat. The scary elements wear off a bit too quickly and you're left with a campaign that isn't very enjoyable.
However, the objectives can be quite varying, and the sound design really shines with your gunfire, motion tracker and enemy screams. The audio is also backed up by some funny banter between somewhat well voiced Marines.











