If you're craving that gritty, high-stakes military sci-fi vibe like 'Aliens: Colonial Marines', you gotta check out 'Starship Troopers' by Robert A. Heinlein. It's got that same blend of intense combat, alien threats, and squad dynamics, but with a heavier focus on philosophy and military culture. The bugs in 'Starship Troopers' feel just as relentless as the Xenomorphs, and the power armor scenes? Pure adrenaline.
For something more modern, 'The Forever War' by Joe Haldeman is a masterpiece. It’s got the colonial marines’ feeling of being thrown into an unwinnable war, but with time dilation messing everything up. The aliens are mysterious, the battles are brutal, and the politics hit hard. If you love the 'us vs. them' tension of 'Aliens', this one’s a must-read.