Theme Aquarium

The gameplay is very similar to the other games in the Theme series, and the graphics are similar to Theme Park. In Theme Aquarium, the player begins with an expanse of empty floor space and the task is to construct a maritime attraction for visitors which must be filled with interesting and appropriate creatures at the same time as dealing with all the attendant challenges of running a profitable business. There are two ways of getting fish and other sea life, either by buying them off sellers or by catching them yourself. Dolphin shows can also be created and serve as the star attraction of the aquarium. Staff must be hired to maintain the aquarium and also to take proper care and attention to the animals.

In a 1999 interview, Bullfrog Productions co-founder Les Edgar stated that Theme Aquarium was produced and tested in the United Kingdom, but implemented in Japan. His intention was to "cross barriers" between the United Kingdom and Japan, and produce a game suitable for both markets, as, due to the success of Theme Park and Populous in Japan, he thought Bullfrog were more successful than other companies in producing games that were successful there. He commented that it sold well in Japan, but would not in the United Kingdom, and that the idea of having the producers in the United Kingdom and the development team in Japan worked. In 2012, Bullfrog programmer Jonty Barnes asked fourteen ex-colleagues about the game, none of whom were familiar with it, with one describing it as "one of those obscure titles", although he also stated that it was known that it was intended for a Japan-only release on the PlayStation.