The final years of Bullfrog Productions are equal parts fascinating and heart-breaking.

This wonderful studio that had only years before brought us games like Populous, Syndicate, Magic Carpet, Theme Park, Dungeon Keeper and Theme Hospital gradually began to wind down towards the end of the millennium, with its final game SimCoaster pushed out of the doors in 2001.

The company's history along with the various cancelled prototypes that it had on the go before its demise has been well documented -- so when I spotted the name of a game I had never heard of before on the company's Wikipedia page earlier this week, what else could I do but dig a little deeper.

Theme Aquarium is listed as a 1998 release developed by Bullfrog, with a name and logo that suggests it is the next in the Theme series. But there are some rather notable quirks to the title. First off, the most obvious: It's a Japanese game. The title was released for PlayStation in Japanese in 1998, and later ported to Windows PC for Europe in 2000.

As if this wasn't already suspicious enough, Bullfrog being a UK-based developer and such, the plot thickens when you discover that the game received a Windows PC port in Europe two years later -- but the Theme part of the name was removed, the logo was completely altered, and Bullfrog's name disappeared from the packaging.

The MobyGames page for Theme Aquarium potentially offers more insight, stating that the game was developed by Tose Co. and Electronic Arts Square. Tose Co. is a Japanese developer best known for creating Nintendo's Game & Watch Gallery series, and for helping out with Japanese ports, so it appears that this would make a great deal of sense. This raises the question, then, of how exactly Bullfrog was involved, if at all.

After asking around, I managed to find a former Bullfrog lead who was at the studio from 1997-1999. Shintaro Kanaoya, currently director of business operations at Microsoft, was lead designer on Dungeon Keeper 2, before he moved from Bullfrog to EA Square. As it turns out, one of Kanaoya's projects at the company was Theme Aquarium, on which he provided localization assistance.

"It's a while ago now, and my memory is a little fuzzy, but the Tose story is basically right," he tells me. "It was developed by them and had nothing to do with Bullfrog, except that we (EA Square) worked with the management at Bullfrog (by then, it was more EA UK Studio than Bullfrog) to use the Theme brand."

As Kanaoya notes, the Theme brand has been rather successful in Japan, and so EA was very eager to slap it on another title for the Japanese audience. "I do remember there being a discussion that the game quality wasn't high enough for it it come out in the West as a Theme game, with the Bullfrog brand," he says.

Essentially, Theme Aquarium was not a Bullfrog game, but utilized the Theme branding and Bullfrog name to generate additional interest in Japan. Even the later port to Windows PC for the European audience had nothing to do with Bullfrog. "The port into English was done by Tose and I worked with them on localization, as well as some other people who were at EA Square at the time," Kanaoya explains.

Another Bullfrog mystery cleared up, then! Notably, if you have access to a Japanese PSN account, you can download the game for PS3, PSP and PS Vita.