An unlocked framerate version of SRB2 with compiled into an EXE, this does not modify gameplay outside of the framerate.

Is using this allowed for submissions?

The guy who compiled it made a video:

At 2:50, he mentions speedrunning as well.

Hello, the usage of a modified executable is currently not allowed for SRB2 as this would make keeping track of different versions really hard and we can't always be sure of what has been modified. For uncapped especially, this video gives a link to multiple things : the executable and the source code. Note that there is also another one curently being maintained by Golden so that's already 3 other versions, compiling it from source code could technically also alter the game in some way so that would be even more different versions.

Now don't lose hope, with how this EXE mod has been improving, i'm pretty sure it could be in the main game soon, it might even already be planned to be added or probably already in the next version.

For Level Runs, as long as the demos don't show any weird differences with the original game demos, the runs would still be verified.

Hope you understand the decision, have fun running the game!