I was really struggling to come up with any games that had mounted combat in them, All I could think of was War of the Roses and Mount and Blade. The mounted combat systems in most rpgs is an afterthought (not surprising considering their dungeon crawl roots) and is given even less consideration in their computer adaptations.
The rules for mounted combat in 5e are vague and not very useful, I remember them being slightly more fleshed out in 3e, which might mean they're more fleshed out in Pathfinder, but that still isn't saying too much.
