I recently installed the 20th Anniversary Edition, and I am having major issues with the controls that are basically making the game unplayable. When I hold down a key, it seems to act as if I'm tapping it repeatedly instead of holding it down. This makes it so I cannot run, crouch, or do the crouching kick in the first level. The controls are practically broken. Can anyone help me?

Same here, found no workaround yet.

edit: From the technical point of view I guess the game is missing/dropping keyboard events (it doesn't receive/handle key-up-events properly). Looks like an overflow/bug in the input event queue (that might be related to the performance issues that have been introduced with the 20th Anniversary Edition).

My controls weren't entirely broken like you describe, but surely very glitchy. Unfortunately I don't know how to fix this either. The only thing I may suggest is to try the 15th Anniversary version, if you haven't already. Both version (15th and 20th) aren't that different. There're just minor improvements in sound and graphic in the new one.

I too am having this problem. Makes it impossible to run from the lion thing in the beginning.