Terrible headline. It’s more of a proof of concept than playable anything. Can’t get passed the first stage due to goal posts not being in the build and it runs at half speed. No one will be enjoying it other than thinking it’s a cool demo.
No that's not true. You can play the game from start to finish at 53% frame rate. You read that there was a 73% framerate version with no enemies bosses or goalposts. That's the one that can't be played past the first level.
Calling this Sonic 2 without specifying which version is imo disingenous, because people think of the Mega Drive version as it was the most popular one. Sonic 2 for the Master System (or Game Gear) as used here is a completely different game and story. Most importantly it's 8bit instead of 16bit, I'm thinking because the calculator also uses a z80 cpu? Cool nevertheless!