What old game is this? I don't know when it was released but, I think it was released after 1990 (Not 3D). It is a Platformer. I believe it is about aliens.
In the first level you arrive in a car and there are these skeletons and you shoot them. As you keep on walking there are buildings (or lifts) that you can use. There are collectible crystal shards. After some levels you will find a big skeleton monster in a room. Another level I remember has you on the top of a building and something/someone is firing rockets at you.
There was skeletons in most of the levels and they looked alien. I doubt the name of the game started with B- . Even though it was 90's game I played it on Windows XP . It is most probably a DOS game. It is similar to Dangerous Dave 2