Because RSDK is a modern engine, some things become easier: sprite scaling, transparency effects (e.g., for Hydrocity’s water), and multi-channel PCM audio. But recreating the feel of the original’s quirky object interaction (like the barrel in Carnival Night) requires obsessive testing.
For more complex mods, you'll need to edit the game's source code: Sonic 3 Rsdk
In 2014, Christian Whitehead and Simon Thomley (Stealth) of Headcannon released a video showing Sonic 3 & Knuckles running in RSDKv4 (the engine used for the 2013 mobile ports of Sonic 1 and 2 ). Because RSDK is a modern engine, some things
The official collection includes Sonic 3 & Knuckles and uses a modified version of the RSDK engine to provide several enhanced features: Because RSDK is a modern engine