Do you like math? No? Me neither, but man I love me some Desktop Dungeons.
The game may seem like your typical roguelike at first glance, but it quickly becomes apparent it's not like its brutal brethren in one key way: it requires the player scope out a floor, check out enemy numbers and available resources. Once you've done so, you plan your strategy based on your level and enemy levels, your HP, MP, and spells.
Desktop Dungeons is definitely one of the more planning-intensive roguelikes I've delved into over the years and I'm not ashamed to say I've whipped out a calculator on multiple occasions to plan my strategy.
If you like roguelikes and want something a little different, this may be one of the best options out there. The gameplay depth paired with unlockable races, classes, and other goodies makes it a well-rounded and excellent addition to any roguelike library.