The small Playstation emulator, for $30 USD it’s not that bad and the software mods for it have matured to the point that they are easy to install and work with. Though at this price point you could also get a raspberry Pi which can do a lot more in terms of emulation.
Armored core is a 3rd person shooter were you start with a basic mech and by earning money through missions slowly customize the mech to suit your playing style. The customization can get a little crazy but revolves around balancing speed, attach power and defense. The original PSX games where unique in that the first game simple entitled Armored Core was a fully fleshed out game while Project Phantasm and Master of Arena were expansions. You could take your saved files from a previous game and transfer your mech's parts and the money you earned to the next game. It is a From Software title so the difficulty especially in the later games can be a little aggravating but fair.