Undeadline is an excellent shooter for the Mega Drive (although it had other incarnations as well). It was developed by T & E Soft and published by Pal Soft.

It's one of my favorite games in the genre. The action is intense, the music is excellent, and the graphics are clean. It might seem difficult, even overwhelming at first, but in time one finds that the level of challenge is just about right.

Undeadline Jap-Eng Translation.zip