Most would probably disagree, but Dragon Age: Origins always sparked Aidyn nostalgia for me.
Aidyn's the better game, but there's my 2 cents worth.
I can definitely see the similarity there, and agree that Aidyn is the better game. Of course, I don't think many other people would actually agree with that, as there don't seem to be a lot of people who appreciated Aidyn in the first place, while DA:O was wildly popular.
Alon D'ar has many strong similarities to Aidyn, but it's a weaker game overall. I enjoyed playing through it with a friend, at the very least.
Not that many games really spring to mind that have particularly strong similarities, though. Aidyn Chronicles just has this really bleak mood that it casts throughout the entire game, a clunky but functional and intriguing combat system, and a really enjoyable stat and character growth system. Exploring everything while trying to get stronger feels exciting and the rewards satisfying, environments and enemies are dangerous and oppressive, and even safe areas often feel cold and barren at times, but rarely in a way that feels like it wasn't intended. I love it.
The King's Field series has a similar environmental setup to Aidyn, as well as an emphasis on exploring everything, but the combat is nothing alike. Still great games, though, and you'd be able to play all of them between the PS1 and PS2.
If I think of something else, I'll make another post in this topic, but the only other thing coming to mind (and not even on the systems listed) is Quest 64, which has a similar combat system, and somewhat similar bleak feeling at times, but is fundamentally a pretty different game from Aidyn Chronicles.
"But...her voice when she's in pain is pretty adorable, you know?" -Saya, Saya no Uta