Gunstar Heroes enters the SEGA Forever collection of classic games, play it for free1
Due to the fact that it runs in an emulator, it's pretty obvious that optimization needs a lot of work, something that SEGA didn't seem to bother to fix before launching a game.
If you haven't heard about Gunstar Heroes, then you should know the game received raving reviews when it was launched on the SEGA Genesis / Mega Drive. Developed by Treasure, the game puts players in the role of twin brothers Red and Blue, who embark upon one of the most treasured SEGA gems of all time.
You'll be burning enemies using flame-throwers or blow them up to smithereens with homing missiles. Gunstar Heroes features local, cross-platform multiplayer over local Wi-Fi, so Android and iOS users can play each other.
The game is available for free, but it's ad-supported, so you'll have to pay $1.99 if you want to remove them. Furthermore, haptic and controller support is included as well, along with the option to save your progress.