SNK vs. Capcom on Neo Geo Pocket was fucking incredible. Having a portable Neo Turf Masters was the cherry on top.

MATCH OF THE MILLENNIUM

Was just so blown away by that game. Hell, you were there- you remember it!

I imported it with expensive overnight Saturday delivery from NCSX- before it arrived, an ad for the NGPC came on TV with footage of the game. I lost my damn mind impatiently waiting for it after that.
Never played much of the NGPC but I liked the joystick. The Wonderswan is another handheld that eluded me, though before the GBA came out I was enamored with the FFI and II (and the SaGa 1, which sadly never got a GBA port) remakes.
Had a Wonderswan Crystal and a Color for a bit. The big draw for me was having a portable Guilty Gear with Petite...
...and it SUCKED. Shitty controls. Really hard to do anything. They released GG Petite 2 later on that was much, much better at least, but then Guilty Gear Advance came out on the GBA and was much better so it didn't matter. That game did have an original character, Fanny, who never made it to the other GG games.
The Wonderswan didn't really seem to be that great for a lot of scrolling (or more action-intensive) games. The screen blur was worse than the O.G. Gameboy, IMO. The big draw were the Square games, and once they started releasing stuff on the Gameboy Advance, the system was dead.
How about the Game Park 32? Anyone own one? I remember reading a huge review on insertcredit.com wayyyy back in the day and I became obsessed with wanting one for a few weeks. Astonisha Story looked cool (then got a PSP port that got a US release, turns out the game wasn't that good). I thought the novelty of a Korean-developed system was neat. Though soon after the DS and PSP came out (PSP especially looking lightyears ahead from a tech perspective) and I quietly forgot about GP32.
Wanted one back then, but never got one. Someone brought one into the game shop Svejk and I worked at and it wasn't quite as impressive as I was lead to believe at the time, but still seemed kinda cool.
Game Gear though, had some nice titles:
Sylvan Tale - my favorite game on the system, an action RPG where you can transform into different creatures. There's a full translation patch. Highly recommended play for anyone who likes oldskool action RPGs and is interested in trying out the GG.
Shining Force - there were 3 of them though only one of them came to the US. I think there are translations for the others though.
Defenders of Oasis - a traditional turn-based RPG with a unique Middle Eastern theme and great music.
Shinobi I and II - I hear so much praise for these games but regrettably never played.
Ax Battler - if Golden Axe Warrior was a Zelda 1 clone, this is a Zelda 2 clone. It's worth a try, though no where near the level of Zelda 2.
Dragon Crystal - this was the first roguelike I've ever played. The genre has probably been done much better nowadays (I'm not really into the genre personally) but it's probably one of the earliest portable roguelikes and one of the first Japanese-developed roguelikes to get released over here in the states.
Game Gear definitely had some good games! With me being all into fighting games, especially back then, I was completely blown away by the Fatal Fury Special port Takara did. It looked great and played really well. Too bad they kinda messed up with Samurai Shodown. Wasn't big on the Sonic games it had, but Ristar was really nice and I played a LOT of Dr. Robotnik's Mean Bean Machine and Pac-Attack.
retronauts has done a few episodes on the lynx recently and it looks pretty decent. graphics were extremely nice for the time, and it looked like it had a decent niche going for software, with some nice arcade ports. i never knew much about the system but it looks alright for what it was.
It had a pretty shitty screen and most of the arcade ports I played were pretty crappy. They just didn't have the third party support and a lot of shitty first-party games from the time I spent with the system. Didn't keep it for very long. I did think portable STUN Runner was cool, though.
I love how they claimed stuff like this was "16-bit and just like the arcade."
