That sounds like a road that could help me get a bit further, thanks!
I added the sensor part to the code, the light pattern is (part) from another ATtiny & WS2812 led strip example program (attiny_pixel_switch/attiny_pixel_switch.ino at master · danasf/attiny_pixel_switch · GitHub). Its easy enough to understand what is happening so that's not a problem. I'll try to work it out with just one color, and if that's the trick I'll simplify the general code a bit.
I'll update as soon as I've had a chance to try it out.
Thanks!