Finding the best PSN games can be trial and error, both due to the relative obscurity of the platform's download services and the further obscurity of the Japanese download services.

However, do not despair, for I have pretty much everything, from Front Mission 2, King of Fighters 98, and Xenogears, to Warhawk, Snakeball, and Go! Sudoku.

You'll be hard-pressed to name a decent PSN game I don't own.  And you might have trouble finding bad games I don't own, come to think of it.

So ask away.  Here's a mini-guide I compiled with a large sampling of the Japanese games I own.

Traditional Horizontal/Vertical Shooter

-Arcade Hits Raiden - It's Raiden, a classic vertical shooter, good in any language

-Cotton Original -

Cotton Original  play sin a similar way to other Scrolling shooter videogames such as R-Type. What distinguishes Cotton: Fantastic Night Dreams from other games of a similar ilk is its bright colourful graphics and its lead character, Cotton. The player controls Cotton, a young witch on a broomstick. The player must blast various monsters and avoid being shot. The player can collect power-ups to enhance their weaponery and unleash a more powerful attack on the enemy. The player has lives represented by an arrow. The player has 3 lives and are allowed one hit per life.

-Einhander - Shooter from Square-Enix, very unique, great music and atmosphere, English voice work and partial text

-G-Darius - Classic shooter action, always great.

-Philosoma - 3D mixed with classic shooter, includes some English

 -R-Type Delta - No challenge here in understanding the gameplay, classic shooter

-Raystorm - Ditto on the 3D mixed with classic shooter, VERY entertaining, includes aerial as well as bomber controls

 Action/Shooter

-Dark Mist - The whole game is in English, Zelda 1 style shooter with dark fantasy theme

-G-Police

Tons of Japanese voice acting, but the gameplay is more or less vehicle-based first person shooting.

-Gunner's Heaven - Plays similarly to Gunstar Heroes and its ilk, very entertaining

-Metal Slug X - Very easy to play and understand, a classic, must-play arcade game in any language. 

-Silent Bomber - An interesting game which I haven't delved very far into, does require some tinkering around to figure out how to play. I believe you're setting bombs on tanks and other enemy vehicles.

Action/Adventure

-Biohazard (Resident Evil) - Japanese menus, (horrible) English voice acting, straightforward enough in action, trial and error in puzzles.

-Tiny Bullets - Looks horrible, controls horribly, can't read it, avoid this atrocious game.

Fighting

-Bloody Roar - Almost entirely English, even english voice acting, shallow but fun fighting game with animal transformations

-Bushido Blade - Sword fighter without life bars, chop til you (or your opponent) drop 

-Dead or Alive - Menus are English, same fighting game you played years ago.

-Ehrgeiz - Square fighter/mixed martial arts contest, easy enough to get into a battle, strange game but not half bad.

 -Fatal Fury Dominated Mind - Just a handful of menus, it's a fighter, what's to figure out? 

-Guilty Gear - Easy to understand menus, hardcore fighting

-King of Fighters 98 - See other fighter descriptions, easy

-The Last Blade - Another fighter that's like Samurai Showdown, but this time there's more Japanese than I would care to read.  Still playable though.

-Psychic Force 2 - The 3D graphics are a bit tough to take (all 3D from this era is), but the aerial-based ranged fighting makes this one unique in the genre.

-Rakugaki Showtime - This is one of those bizarro Smash Bros./Power Stone-type games, and is entirely Japanese, but the gameplay is very fun and straightforward once you play it for a bit.

-Samurai Showdown 1 and 2 - You can't read what the characters are saying when they taunt, but aside from that, you know how these fighting games work.

Miscellaneous 

-Bishi Bashi Special - Very much like Wario Ware. Actually can be challenging to understand this context-sensitive game, if you're not up for a little guessing, avoid

-Ore no Ryouri - The cooking game that started it all, really.  This one has a language barrier, but it's worth overcoming.  FANTASTIC game.

 -Panekit - I'd like to think of this as the spiritual precursor to Banjo Kazooie:  Nuts and Bolts, since you're building a vehicle to traverse new terrains.  But some  Japanese knowledge is definitely helpful.

-TOMARUNNER! - Wacky game with a significant language barrier on the tutorials, basically you're running around hallways and neighborhoods according to a rhythm-like technique. If you can get past the tutorials, you'll surely find weird charm.

-Um Jammer Lammy - Actually includes an option to play the entire game in English, neat rhythm game involving song lyrics.

Action/Platformer

-Adventures of Little Ralph - Fun little platformer, just a few basic controls and you're gold

-Jumping Flash 2 - More or less similar to the first game, not difficult to figure out, platforming action.

-Saru Getchu! (Ape Escape) - Can't read a thing, I made a mistake in getting this one, even though it does include the classic "catch the monkeys" gameplay.

Sports

-Carom Shot 2 - Almost all English, very enjoyable billiards game.

-Everybody's Golf Putter with Toro - Completely English if bought from the Hong Kong store, light on content but it offers a relaxing 9 holes of minigolf, either competitive or single player, no online. 

-Wai Wai Tennis - Terrible tennis game, easy to understand, sucks to play.

-Waiwai Baseball - Why do I keep buying Hamster games?  Just...don't.  Here's a hint.  If it isn't a port of some other developer's work and it says HAMSTER, avoid like the plague.

Game not pictured.

Arcade Action

-Arkanoid Returns - Who doesn't love Breakout? It's back here, and very easy to understand.

Puzzle

-IQ (Intelligent Qube) Final - Very unique 3D puzzle game which you might have played before, set a trap for the cube that is rolling towards you, disintegrated bits at a time. Language barrier is almost nonexistant.

-Jigsaw World - This was Nippon-Ichi's first game, and it lets you complete a jigsaw puzzle on a timer. Now, there is a language barrier to overcome, but even a small child could understand the gameplay. Various modes, fill in the pieces based on the examples. If you're a fan of jigsaw puzzles, this one is for you.

Kula World (aka Roll Away) - Also contains mostly English, action puzzler in which you roll a ball across traps and switches, very fun.

-Money Idol Exchanger - Can't get more straightforward than this, another puzzle game, has you swapping change for other change to set up combos. Easy to play for English speakers.

 -Mr. Driller - This game speaks the universal language of puzzle fun. Although completely Japanese, the menus aren't difficult to comprehend.

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-Puchi Carat - Breakout style puzzler in which you must break the colored balls above your head, think Breakout meets Puzzle Bobble, Japanese menus but nothing too complicated.

-Puzzle Bobble 3DX - Classic puzzle action in which you must chain colored jewels by shooting them upwards at other colored jewels.  All the menus are Japanese, so you'll have to learn where everything is first.

-Tall Infinity - This game is another "roll something you're standing on" puzzler like Devil Dice, except this time you're building a castle upward by aligning colors. Game has English, and even if it didn't, you'd get it. Highly recommended.

 -XI Jumbo (Devil Dice 2) - Well, color me surprised. Despite gameplay that is very straightforward, navigating this game's lobby menus are a monumental task if you don't understand Japanese. Align the dice gameplay is great fun, but it will take some doing to get past the language barrier.

Racing

-Crash Bandicoot Tag Team Racing - Okay, you've probably played or heard of this game before. Well good. You know how it plays. But all of it, from the menus to the fully-voiced characters, is all Japanese. I'd say wait for a US release, if it ever comes.

Strategy

-Culdcept - Card/board game.  If you've played this game before, get it because it's the same thing.  Otherwise, avoid playing the Japanese version because you won't be able to figure out how it works.

-Front Mission 2 - Strategy RPG with mechs.  This is a reluctant recommendation, because the game features a ton of English for the actual gameplay, yet the buildup to the battles will be completely lost on you.  If you don't care about story, get it.  It's fun.

RPG

-Alundra - Another action/RPG but you'll be lost without a knowledge of Japanese, I assure you.  I couldn't make it to the second story sequence without a guide.

-Brave Fencer Musashi - Action/RPG with very little English, but the gameplay is straighforward enough.

-Xenogears - You cannot play this game unless you read Japanese.  Don't even try.

Adventure (Traditional)

-Athena:  Awakening from the Ordinary Life - It's a traditional adventure game, with tons of text, so I don't even need to tell you how difficult this is to play without a thorough knowledge of the Japanese language.