A day i wasn't hoping would come but i have to admit due to ZDoom and GZDoom Engine Limitations i won't be able to successfully and accurately recreate all of SRB2 Features, Most of Sector types, and Behaviours of enemies as well as various other effects are simply impossible to recreate without having to modify the Source code for those engines, even the latest Dev Builds of those engines don't contain what I need.
What do you need Exactly ?
- Scale Player ingame. and also Change Height of Player during Spindash, These won't happen anytime soon according to developers of the ports.
- Track Linedefs angles to Force Knuckles to look at them while climbing.
- Hundereds of Linedef types and Sector types, Recreating these with a combination of ACS and Existing effects would be a Pain in the butt, and even then it won't be accurate.
- Proper Slope Physics similar to those from SRB2, The upcoming 2.2 SRB2 Update will use those heavily and there's no way to Port those without direct engine modification.
Fate of zSRB2 ?
I'm going to leave it here the way it is, Currently none of the above features are needed, The game now features over 20 Maps and is in a playable State, However not so accurate, So I recommend you to play the original Instead, It still has an active community and Multiplayer even today, else you're welcome to Pick it up where i left and Continue with maybe an engine modification ?