Namco x Capcom was a Japanese-only game developed by Monolith Soft and published by Namco. It featured a major cross-over between many characters from the Namco and Capcom video games.
It even featured very well drawn anime-style cut-scenes.
The game was a cross between action-rpg and tactical-rpg. You could play many different characters and interact with others.
Though it sounds like a dream come true, Namco x Capcom didn’t receive a superb review scores in Japan. It was a moderate success financially. Besides a large translation-cost issue, I can’t believe Namco never brought this over to America or even Europe.