Twinbee is a game series by Konami, which consists mainly of vertical shooters, although it has delved in other genres as well. It stars the eponymous bee-shaped robot Twinbee and its "female" counterpart Winbee. In some games a green bee named Gwinbee appears, which acts either as a powerup or a playable character. Unlike other Konami shooters, Twinbee has a cuter design and ambiance (like Fantasy Zone), which is referred to by fans as "cute 'em up".
Here's Twinbee, the one and only original. It's amazing to see how much of the series' mechanics already were in this ancient coin-op. The most unique, of course, was the aforementioned bell power-up system. Regular yellow bells will just add points to your score, but if you shoot them enough, they'll change color and become useful powerups. A blue bell means speed up, the white one powers up your weapon, the red stands for shield and the green will add mirror options that mimic your ship's fire. Twinbee and Winbee can also interact in several ways: they can unite (by holding hands) to shoot a powerful fire bullet. Perhaps more fun and effective, one ship can push the other to produce a spread bullet shot. Also, instead of getting killed outright by enemy bullets, your Twinbees will lose their limbs. When they're fully incapicitated, a little ambulance comes out from the screen, ready to resuscitate them - if you can make it.