You are supposed to delete nvram and hi score files (if your version of mame supports them) before you start recording and also before you playback the inp. That is the best way to make sure the game behaves exactly the same for the playback. As mentioned, 'randomness' really doesn't exist in computing and is based on 'seeds' (numbers) -- arcade games used things like the hi-score table to seed the randomness, so if you try to playback an inp with a different hiscore table (for example), the enemies may appear in totally different places and you will look like you are 'wandering around like an idiot' when you playback hehe.
You also should use the same exact version of MAME for recording and playback (ie you can't record in MAME 0.35 and expect it to playback in MAME v.035.
ahofle - i've been assuming that if you have the following 5 pieces, you can reproduce the game:
mame version
name of rom (e.g. "robotron")
robotron.inp
robotron.cfg
robotron.nv
does that sound correct? i know that is sufficient for me to reproduce games on my machine, but i'm not sure it's sufficient for someone else to reproduce my games on their system.
(+_+) - i tried your .inp and got the "wandering around" effect. there was obviously something out of sync. are you using mame 0.133? you can just always delete your .nv file, as ahofle suggested, or you can do what i do:
in your mame directory, make a folder named SavedConfig.
copy nvram\robotron.nv SavedConfig\robotron.nv
copy cfg\robotron.cfg SavedConfig\robotron.cfg
make a file named robotron_capture.bat:
copy SavedConfig\robotron.nv nvram\robotron.nv
copy SavedConfig\robotron.cfg cfg\robotron.cfg
mame -skip_gameinfo -record robotron.inp robotron
make a file named robotron_playback.bat:
copy SavedConfig\robotron.nv nvram\robotron.nv
copy SavedConfig\robotron.cfg cfg\robotron.cfg
mame -skip_gameinfo -playback robotron.inp robotron
now to play a game and capture an inp file: just double-click robotron_capture.bat.
when sharing an inp file, include also the 2 files from SavedConfig.
to playback the current inp file, just double-click robotron_playback.bat.