One of the biggest (and buggiest games) to hit my JC life was this game called “X-Com: Enemy Unknown”. If you haven’t played it before — and if you’re not in my age group then probably not — you don’t know what you’re missing. Maybe you can search on the Internet for the original version or one of those spinoffs with improved graphics and sound.
The role-playing element was excellent as well as the weapons/capabilities tree that expanded once you hire scientists and allocate them to various fields of research.
My group of friends spent loads of time with this game, and even though it was one of the buggiest games we ever played as DOS4GW would crash repeatedly, the great gameplay kept us coming back for more.