The PC Engine (a.k.a. the TurboGrafx-16 in the US) was a particularly powerful 8-bit games console with 16-bit bits, that was both incredibly popular in Japan and a brilliant platform for arcade conversions. It even managed a couple handheld versions of itself, though you really don't have to go looking for them. There's a much cheaper alternative, as the open-source Caanoo handheld can now emulate the PC Engine for free, via the just released Caanoo-HUGO. Download it here.