Microcorruption is an embedded security CTF. I’ve completed up to Chernobyl, which is 17 levels in, plus the tutorial.
This is an embedded systems CTF, emulating TI’s MSP430. It was really, really fun. It’s generally low level, assembly stuff.
I started this CTF 5/24/2016 and finished up to Lagos (the sixteenth level) on 6/23/2016. Not having worked on it for a while, I wrapped up with Chernobyl on 3/7/2017. I think this is a good stopping point for me.. this one took awhile and having looked a bit at the next level (Hollywood), I think it’s too time consuming for now.