I tried about a year ago and I couldn't get past the first proper level - I just didn't grok it.

In the meantime, I've done quite a lot of CTFs, reverse engineering, binary exploitation etc. I tried again yesterday, and I'm already up to "Algiers". I guess that just goes to show that it isn't really suitable for absolute beginners like I was, unless you're very perseverant.

It's a lot to absorb without some background. I was playing it about a year ago until I ran out of free time (still want to go back and finish), but it brought back a lot of memories of programming assembly in college, which probably helped.

I think as long as you know C and know how a computer works (ie: stack, heap, registers) you could at least get to level 10'ish w/o too much trouble. Granted if your only programming experience is languages like Java/Ruby/Javascript/Python that hide a lot of the details of how the computer really works it might be more challanging.

I got stuck at the beginning because I didn't know what endianness was, and there was no help or hint about it in-game - but after that it was just fun challenges at just the right pace for me, with enough hints to know what to google and what to try. Getting stuck is fine, as long as you're too stubborn to give up :)