Arena movement, casting and ending turn mimic the original:
QWE
A D : cursor movement
ZXC
S: Select
K: Cancel casting or movement
0: End turn
Additionally the number keys 2-8 will toggle frame highlights for the corresponding wizard and the TAB key will toggle colour-coded bases.
If you're looking for the definitive remake of Chaos, look no further than Richard Quirk's outstanding android version (available here at the Google Play Store). I'm very grateful for this version keeping Chaos alive and well, not to mention widely available.
Thanks also to this Chaos disassembly project that I stumbled across at: https://zxnet.co.uk/spectrum/chaos/