Years ago, I used to play spelunky classic a lot, and I've gotten back into it recently. I prefer it to the HD version in many ways, but the one thing that always bothered me is you can't start/stop running in mid-air.
This is especially annoying when:
-Using a cape/jetpack. If you are running when you first leave the ground, you move really fast through the air until you touch the ground again.
-Running and jumping, then grabbing onto a ledge/ladder/rope. Even if you let go of the run button, when you jump off you'll still be running.
This was changed in the HD version, so now here's a fix (if you consider it one) for classic. I can't guarantee this was the best way to fix it, but it seems to work well. This was modified from v1.3.http://www.filedropper.com/spelunkyv13runfixwindows
The code change is in Scripts/Characters/characterStepEvent. Here's the diff: