Aeon Genesis is a ROM translation group run essentially by one man, Gideon Zhi. He is regarded by most of the emulation community as being non human, due to the sheer amount of games he has managed to translate.
To be more precise, Gideon is actually a hacker, who prepares ROM files, dumps and inserts scripts, and irons out any bugs so that translators (he works with many different translators) can work their magic, and make games originally intended for a Japanese target audience playable for English speakers. Compared to the other main ROM translation group, Dejap, Aeon Genesis have far more finished projects, although to be fair, Dejap do a lot more complex games (eg Star Ocean which needed hours of hacking and work just to get graphics packs available so that the game could run) whereas Aeon Genesis tackle simpler games (but a hell of a lot more of them).
Games that are currently* on the projects list at the website are:
As you can see, there is a fairly nice sized list of games there, which just goes to show how un-human Gideon must be. He updates his website relatively often (compared to some other unnamed people *cough*), about 3 times in the run up to Christmas, and when a game is released it is normal for him to post some bug fixing updates in over the next few weeks - Gunman's Proof went from version 1.00 to version 1.03 (3 updates) in one week, with a major bug fix each time.
Although I have not played all of the games that the group (well, it's not really a group. More of a sort of hive mind with worker translators who report to the All seeing, all knowing hack-god) have translated, and some of them look kind of bad, some are absolute gems. Shin Megami Tensei is brilliant, Live A Live is great, Rockman and Forte is one of the best Mega Man games (Rockman is the Japanese name for Mega Man. Gideon is so nice that there are 2 patches available for that game - one to give you the Western names (Mega Man and Bass) and one for the Japanese names , Rockman and Forte) I've played and Front Mission Gun Hazard, when it gets finished, will be superb.
Gideon's site also has a message board, a chat page, and some miscellaneous documents which proved how tos on a number of difficult techniques in ROM hacking. There's a great guide for vanilla hackers who have no clue what they are doing (like me) which provides a list of files to download and then proceeds to walk you through changing some text in a game, Army Sergeant style (YOU MUST NOW OPEN THE HEX EDITOR. SEARCH FOR "NATSUME". REPLACE IT WITH THE TEXT "IMIDIOT". IDIOT. NOW YOU HAVE TO SAVE THE FILE. YOU DO THIS BY SELECTING "SAVE" AND PRESSING ENTER. IDIOT) - overall, I'd say that Gideon is one of the hardest working people in emulation. All respect to him, and let's hope he finishes FMGH DAMN SOON. IDIOT.
A few noders have pointed out to me that some of the games that have been translated are available in English anyway. For example, Puyo Puyo is the same as Kirby's Avalanche and Dr. Robotnik's Mean Bean Machine (thanks to yerricde for that) and that Rockman 2 is the same as Mega Man 2 (thanks to Servo5678 for that one). As to why these games were retranslated, I'm not sure - sometimes it may be as practice for the hackers and translators, or it may hvae been decided that the original translation was not good enough. This happened in the case of Final Fantasy IV which was released in the West as Final Fantasy 2, but the translation was bad, and the game was dumbed down. This lead to a group retranslating the Japanese game from scratch, and the same reason may have applied to these two games mentioned. Anyone know of any other games above which are already available in English?
Update on 21/6/03 - well, Gid has released some good patches, notably King of Demons. He's also announced both Treasure of the Rudras and Shin Megami Tensei II amongst other. Looks like TotR should be out in reasonably quick sharpish time, although apparently if we ask when it will be released, we all get shot. So, er, don't. Please.
The Treasure of the Rudras patch was released a short time ago, and predictably enough, it's brilliant. I'm off to play it some more.
Update after lots of days: I'm afraid if you're expecting me to keep this writeup updated you are sorely mistaken. Suffice to say that recently, Gid has released Front Mission Gun Hazard and Star Fox 2, plus a heap of other stuff. Go and play you zany people.
Sources:
The Aeon Genesis website - http://agtp.romhack.net
I'm sorry about any spelling mistakes in the names of games - I'm taking all this off the website. If you spot any, please let me know.
* - time of writing 22/01/03.
Thanks to yerricde who spotted some spelling mistakes.