Emulation is pretty solid, but, it's too barebones to be notable for anything either.
Playing the NES games require you to play with Y+B because X+A are swapped, Absolutely no mapping options.
Plus side is that SNES and Genesis games have a good control scheme (Snes is a given, but it's easy to fuck up genesis)
PC version outright has no Exit Program feature nor display settings.
Castlevania uses the original release which has the Sprite Draw crash, which explains the massive amount of flicker.
I'm going to give it the ol' GPD WIN optimization test, but what I've red on the reddit, it's probably not going to go so well.
Also the Twitter stated this is "the first", so buying this isn't too bad. if anything someone will probably crack the .bin to replace the roms.