I haven't seen a full-screen scrolling Tron/Light Cycles game on the ZX81 so this week I created one - Astro Bikers - just for fun.  It's got all the usual stuff you'd expect from my ZX81 output so go download and play.

I am presently between jobs so it will ask for a voluntary donation of $1 but please skip past and download for free.  If you have fun then consider making a tiny donation later.  No obligation though, very few people ever make voluntary contributions for Spectrum or ZX81 games.

Regardless, enjoy!