If you want to spoil other games that straddle the imagined psychogeography of the casual/hardcore divide forever, the Rebuild series [official site] is a good place to look. On the surface, these strategic games of zombie uprising aftermath survival and urban reclamation are simple, colourful resource-gathering exercises, but they're cleverly balanced and squeeze plenty of flavour out of the setting. Since the earliest Flash incarnation of the concept, Sarah Northway's games have appealed to me - ideal to dip into during the eternal coffee break of the soul.
The third title adds factions, a splendid revamped UI and much more. I've played the early versions of the Early Access release but now, with the campaign complete, the game is ready to launch.
I dipped into the campaign this weekend. It takes place across a dozen cities, the difficulty increasing as you go. On top of that, there are survivor relationships to handle, loot to gather, 50 types of building to construct - everything you'd expect in a bulked up strategy-survival game of this type. It'll take another few hours of play to figure out if the campaign structure is a comfortable fit - it risks becoming repetitive if each city doesn't distinguish itself - but almost everything I've poked at so far has more depth than I expected. That goes for tech trees, characters, mission types and loot.
The greatest advance over the previous games is the UI. It's clearly improved and, hand in hand with the presentation, can serve to make Rebuild seem like a simpler thing than it is. Sure - it isn't a grand strategy survival sim, but it's a tight turn-based brain-tickler that has more fun with the zombie theme than a hundred first-person shooters.