Freedom Planet exists (very much legally), my engine isn't infringing on SEGA's intellectual property any more than that series is doing.
While there are a lot of similarities to Sonic 2, these are a homage and I am not trying to mislead customers into thinking that this is an official Sonic game (the efforts include, but aren't limited to, having a different visual style and character design, having a significantly different in-game HUD layout so that screenshots are easily distinguishable from that of Sonic 2, and having a clear and prominently displayed official name - without similarities to the series - as the page banner, in the screenshots, and in-game).
Besides, modern Sonic games - which should be more recognizable to a consumer than the decades-old Genesis originals - have branched out to have a lot of mechanics that this engine does not replicate, such as the character customization in Sonic Forces, 3D environments in Sonic Adventure and Sonic Heroes, and the ability to transform into a werewolf in Sonic Unleashed. Standard platforming movement - including inertia, sliding down slopes, etc - is too generic to be protected by copyright and trademark laws. (Are you going to post angry comments on Exo One next because you can roll down slopes in that game?)
Finally, this is an asset pack, not a game, so I'm not even directly competing with SEGA. What my customers choose to do with the engine is their responsibility - and using the engine to make a Sonic fangame could be a copyright or trademark violation - but you could make a Sonic fangame with Unity, Godot, or raw machine code as well, so there is nothing in my engine that specifically enables that type of despicable crime.
My asset is not illegal, and if you're going to keep slandering me I might need to take actions against you. I notice you registered very shortly before making your comment and don't have any other activity, which could be a sign that you're using an alternate account in a clear violation of the Itch terms of service...