The board game Aliens: Bug Hunt combines dungeon crawler and tower defense mechanics to bring the frantic gunfights of Aliens into a fast and friendly game.
Hrm, totally not my type of game I'll admit. Dungeon Crawlers are a bit iffy after Gloomhaven as that raised the bar so much, and I've never been a fan of plastic-centric games in the first place.
That being said, Nemesis already provides this, in a lot of ways. And it's much smarter than just shooting aliens.
Honestly project elite is the best alien blaster game if that's what your looking for. And even Aliens: Another Glorious Day in the Corp works better with an awesome endurance deck mechanic. No need to go second hand market either if you don't want to.
Legendary Encounters: An Alien Deck Building Game is a different kind of beast but it's really cool too. The way the enemy reveal works is very thematic and the various Objectives make a great use of the Legendary enemy-river system.
Never had a chance to play this but I researched it a bunch and I almost picked it up a couple times. Looks like a fun dice-chucking romp. It uses the tile based map reveal that Sub Terra and now Clank Catacombs has too. Sadly it seems to be out of print now and according to a BGG comment the publisher may have lost the license for this one too.