The explosion sprites are the ones in Sonic 1.The ground speed cap from Sonic 1 is still present.The spike damage behavior works the same way it does in Sonic 1.Further, the sound for when Sonic spins in Sonic 1 is heard as there is not yet a specific sound effect for the spin dash. The spin dash is a work-in-progress, as Sonic and Tails can only charge it once.The sprite of him getting up would later be polished and reused for when Sonic leaves his 'lying on ground' idle animation. There is a mechanic where Sonic rebounds off walls if he runs into them at high speeds, using sprites that became unused by the Simon Wai prototype.The music and invulnerability last until the end of the Act. Invincibility doesn't show the star effect, though the music is still played.2-Player mode is even less complete, due to all sorts of odd glitches and not being enabled for every Zone.The AI is also much simpler: Tails copies Sonic's moves and makes no attempt to keep up with him. If Tails gets hurt, he can lose rings for Sonic. Further, Tails cannot complete a level on his own, since the game only loads the signpost when Sonic approaches it. At this point in development, Tails is quasi-independent: Player 2 is able to control Tails, except he will also follow Sonic.
