GameMaker Legacy is GameMaker 8.1 or lower and GameMaker Studio is anything modern (I.E GameMaker Studio and Studio 2 or better).
Sonic DashEngine, the latest Sonic game development framework for GameMaker.
Sonic DashEngine is a game development framework that runs on top of GameMaker; an existing game engine/framework.
What can Sonic Dash Engine do? It can do almost anything that has been done in previous classic Sonic The Hedegehog video games; rather that would bethat would be moving platforms, or switch-activated doors to mutli-path movement, level-transitions/concatenation or online multiplayer*.
Now that you have an idea of what DashEngine is and what it can do now lets get onto why you would want to use this Sonic The Hedgehog game development framework over others like Sonic Max, Flicky 8, or Sonic Studio Engine GM8 GMS+, or Pvic's Gmate Delta.
You should use DashEngine if you have GameMaker Studio 2 and you want all the features that GameMaker Studio 2 has to offer but with the ease of making your own Sonic The Hedgehog fan game with the amount of tools built into the software. While DashEngine is not the best of Sonic The Hedgehog Frameworks for GameMaker Studio 2; not by a long shot; it can get the job done for anything that you might need to do in a Sonic The Hedgehog fan game.
