Gotzendiener (PC Engine)

This is an action-RPG, made by Gainax. Or at least, they were involved in it's development in some way. It's odd that Gainax's most famous series tend to be about mecha (Gunbuster, Gurren Lagann, Evangelion, etc.), but their games usually have fantasy settings with no mecha at all (Alisia Dragoon, the Princess Maker series, etc.). This game is no exception to that rule.
The scneario is pretty cool: You play as a maiden who's been captured by an evil demon, and as usual, a brave hero came to rescue you, and though he did successfully kill the demon, he was mortally wounded during the fight and quickly followed the monster into death. So you take the hero's sword and set off to find your own way out of the castle.
You go around the isometric stages, solving puzzles and occasionally fighting monsters (I guess the hero must have killed most of them on his way up?). You don't have to worry about understanding Japanese for this game, as other than a couple of animated cutscenes, there's no text or dialogue, and there's nothing in the cutscenes that you need to know to progress. There were a couple of points where I got stuck in the game, though luckily there's a really excellent FAQ on GameFAQs, that not only contains a full walkthrough for the game, it also translates the plot and provides details of the tie-in merchandise that was released for it!
The game looks good, with nice animation and sprites that are detailed despite also being tiny and low-res. The music is good too, having a slightly arabian flavour to it (some people online have compared the game as a whole to Prince of Persia, and there is definitely a similar feel to it in looks, sound and atmosphere, I'm not really familiar enough with PoP to say whether the similarities extend to the game itself. (I'm mostly unfamiliar with it because I tend to die as soon as the first enemy appears.))
The only real problem with the game is that it is incredibly short and, other than the parts where I got stuck also very very easy. I completed it in less than two hours, and as I've mentioned plenty of times before, I'm terrible at games. It's definitely worth playing if you can find it cheap/free, but copies online seem to go for about £30, which does seem a bit much.

One Piece Mansion (Playstation)

The thing this game is most famous for is having nothing to do with stretchy pirates. It also has nothing to do with mansions either, so it all works out for the best in the end.
You play as the manager of an apartment block who looks kind of like Gaz from Invader Zim, and you've got to keep all your tenants happy so they don't explode. You do this by strategically arranging their apartments. How do you know how happy they'll be? Each kind of tenant has a bunch of arrows coming out of them when you highlight them. Blue arrows mean anyone in that direction of the tenant will be made happier by their presence, red arrows mean that their neighbours will be made less happy. Further complicating matters are criminals who will randomly move in, spreading bad vibes around them, and occaisionally wandering the building causing havoc. To get rid of them, you have to make good use of your more annoying tenants to drive them out, as well as running around blowing a whistle and/or spraying a fire extinguisher at them when they go on their mischeivious jaunts.
In story mode, you go through a finite amount of stages, each with an objective, such as "Build 30 rooms!" or "Make $20000!". If you run out of money, the game ends. There's also an endless mode, with no objectives, you just keep building upwards until you run out of money.
Story mode is excellent, the stages are fast-paced and don't take too long to do, the only problem being it's quite easy and very short (I completed story mode without failing a single stage.). Endless mode is also very easy, and obviously lasts a long time, but has a different problem: the lack of objectives makes the game very boring. You just build tenants as soon as they come along, then wait for either more tenants to appear, or for that month's rent to be paid, with only the occaisional criminal to break up the monotony.
One Piece Mansion is good, and definitely worth playing, I just wish it had some kind of mode with infinite, randomly generated mission objectives.