Magirune 2

A robust example of the "magic tower" genre with an interesting conceit of progressing through a number of separate, sequential regions (i.e., you'll find the weapon at the end of region 1 that lets you start attacking the enemies in region 2, etc.) Each is a reasonably deep stack of rooms that were fun to understand and (eventually) solve. The game's engine for me played more smoothly than similar games built in RPG Maker. Note that dialogue is sparse and suffers a bit from translation, but you're really here to puzzle out the towers. Also, has a nice surprise for full completion, [spoiler] a complete copy of their first Magirune game, made in this engine[/spoiler]. I would recommend playing on Hard. One difference with other games is that enemies respawn when you leave a floor - on Normal enemies give full XP the first time they're killed and one XP after, while on Hard they only give XP on the first kill (which is part of the puzzle of overcoming each area). Potions heal less on Hard, though the game is forgiving enough that you'll have several left over at the end if you're careful (even if you make a few mistakes). As these are the only differences, Hard really just ensures the puzzle stays a puzzle the whole time through. (Worth noting there's enough keys to open all doors though you still have to be careful in managing them.)