Maybe I should pop in an original keyset as an option - I think the original uses the caps key maybe. I'm pretty sure it's weird on a modern keyboard layout. I think the version on the bbcmicro site keymaps it by default, in any case if you want to revisit the original its here:
https://bbcmicro.co.uk/game.php?id=432
Edit: I'm going to have to go and revisit it again now... I was sure it was infuriating on a modern keyboard.