Bullet Heaven is a "bullet hell" type of shooter game with forced scrolling. You fly your character upwards on the screen while shooting at a large number of enemies. The game is a spin-off from Epic Battle Fantasy 3 and contains characters and creatures from the game.
You can play as five different characters, but they all handle the same. The game is mouse-controlled. Your character follows your cursor, and you click to shoot. Left clicking fires your default weapon, while double-clicking activates a more powerful weapon that takes time to recharge. You also have a limited amount of "bombs" that you can trigger with the space bar.
At any given time, there are a lot of enemies and bullets on the screen. It may look impossible to get by without getting hit, but it's not as bad as it looks. Although your character is about the same size as a small enemy, there is only one pixel on the character that can be hit and cause damage to you. You can dodge through the most narrow of gaps, it just doesn't look like it. When you kill enemies, they may drop power-ups or gold coins for you to collect. Power-ups may temporarily give you better damage, a shield or increase your hit point. Gold coins can be spent on various upgrades for your character. Any upgrades you purchase apply to all five playable characters.
There are 24 levels and a Survival mode level. When you complete a level, you receive a "rank", which is a grade for how well you did on the level, depending on how many enemies you managed to kill. Each level can be replayed to gain more coins for upgrades and improving your rank on that level.