Huge playlist archive with Kempston Mouse games: https://www.youtube.com/playlist?list=PLxOanVBhqd3tM1Ov2sGHI177WdlY0wali
Gunman is a Russian game from 1999 made by Alien Factory / Sage Group, and you have the possibility for choosing to play with Kempston Mouse in this game. It seems like it is some kind of High Score game with only one level, but if you have Kempston Mouse it is worth checking out!
If you do not have a Kempston Mouse or Beta Disk / TR-dos which this game is for, you can play the game in an emulator that supports these things and play it with your PC mouse. ZX Spectrum Next can also run this game. The game can run on a standard ZX Spectrum 128k with tape recorder if someone changes the loading routine to tape format.