But maybe you were thinking of something even better, like in the below video, for instance. This is a video made in-game (Planet Coaster) using the feature that lets you ride the rides you create. This creation is nearly unbelievable, but you can download it and put it in your park if you are skeptical. Everything, including the Xenomorphs, are constructed with bits and pieces available in the game.
Would have been cool if an Alien queen jumped off the back of the coaster when you returned, just like in the 2nd movie.
I once made a rather significant mod for the Ascension level of Crysis, which is the one you were stuck in a Vtol the whole way. I made it so you could land it and get out. I added a few objectives where you salvage a Hovercraft and Helicopter, driving the hovercraft to a warehouse, and parking the heli on a helipad on it's roof. I also opened up the blocked tunnels on the train tracks, and added a train track bridge across an area with water, to connect to a little loading dock I turned into a small train station. The 3rd objective is the one I'm struggling to remember, but it involved going inside one of the tunnels to gather intel on something I think, which was inside a crashed train car. I placed a guy with a rocket launcher inside the tunnel, and a couple with assault rifles, whom were tough to deal with.
I made a narrow corridor for the hovercraft by clearing trees on the side of a ridge, and it was a hoot to drive on it. I placed a few Ceph Troopers here and there, and a Ceph Hunter right on the path just before the warehouse. If you were good at driving it you could drive it under it's legs and take shelter in the warehouse. The final objective being defeat the Hunter, for which there were weapons in the warehouse. I also put a barracks and friendly troops on the other side of the path where the warehouse was.
I also placed an enemy heli on a far ridge, and 4 KPA troops, for which I also placed an AI trigger point on the helipad to make them come investigate via a flight path I scripted in. All was going well until the final testing revealed the KPA would not respond to the AI trigger. It's a shame too because it was really fun to play other than that. The problem could have been partly due to the spec I had at the time, which made the editor run kind of laggy. They say with lower spec you need to save your editing progress often too, and I may not have been doing that enough. At any rate I learned not to get involved in complex mods unless you have spec that can handle the editor you're using well. Otherwise by the time you get better spec, you may have become disinterested in finishing it, and as well, players in general disinterested in the game.