I just got my subscription copy of PC Gamer (UK), and there were various games on it. I quickly played through a lot of the commercial demos, not very impressed.
I then came across Pontiflex. Within 10 minutes of working out the basics - I hooked, 30 minutes later I had completed the demo and wanted more - so bought the full thing. I still only first started playing it less than an hour ago! 
This is the first time I've bought a shareware game before - so was a little aprehensive to splash the cash - but the online purchase process and download worked brilliantly.
I suspect it will be a while before I put this down - worth every penny - I've told all my friends too.
Great!