About the Space button...

[Vilis]

When I first started this game, I tried many buttons to find a replacement for left-clicking. I didn't. Then, I once pressed space accidentally and it did something it previously didn't: act like left-clicking. However, that's not always the case. In Act 1 it never does it and switching stories it sometimes works and other times it doesn't. Wtf?

[Anonymous Coward]

I managed to find a thread about a problem similar to this: http://ks.renai.us/viewtopic.php?f=45&t=4919

Or perhaps you're trying to use spacebar in decision points? That won't work 'cause at decision points you use enter to advance.

Other than these, I dunno what might be the cause.

[#120]

When I first started this game, I tried many buttons to find a replacement for left-clicking. I didn't. Then, I once pressed space accidentally and it did something it previously didn't: act like left-clicking. However, that's not always the case. In Act 1 it never does it and switching stories it sometimes works and other times it doesn't. Wtf?

That's a bug. If you use alt+tab or alt+enter hotkeys space will stop act like left-clicking.
Fix: press alt.