Tomba! is a side-scrolling platformer in which players control Tomba, a wild boy on the search for his grandfather's bangle that was stolen by some evil pigs. Although Tomba is normally restricted to a two-dimensional plane, there are certain points where he can jump or climb onto a new plane. Tomba's main method of attack is to jump on top of enemies to grab them, allowing him to hop around on them before throwing them away. This can also be used to open other objects such as eggs or treasure chests. Tomba is also able to use various projectile weapons such as maces and boomerangs and can swing on branches and poles.

The game is based around a mission system, where the main character's (Tomba's) skills are employed to complete various tasks. Completion of a mission gives a certain amount of adventure points (AP) which are required for AP boxes which contain food (which gives you AP and restores 1 space of vitality) or items, and you may for example need 50,000 AP to open one. AP is also used to gain access to special places or information later in the game. Not all missions are necessary to progress in the game, however, they are required to achieve full completion. There are 130 events (missions) in the game, many of them rely on other events to be completed.

Tomba! is set on a group of islands in the middle of an ocean which do not appear on any map. Formed with great provinces in the north and smaller islands in the south, the region is home to peaceful people who lived in tranquility for many years. The island was once a beautiful place, home to birds and plantations.

The protagonist is an energetic pink-haired youngster named Tomba (Tombi in Europe). One day, seven evil pigs appeared, and using their magical powers, they mutated the surroundings into a bizarre landscape. The underlings of The Evil Pigs, called the Koma Pigs, stole Tomba's grandfather's bracelet and a substantial amount of gold through a strange lust for it.

Tomba's quest is to fetch his bracelet, which requires trapping the Evil Pigs along the way. Trapping them involves finding the Evil Pig Bags, which are keys to entering each realm of each Evil Pig. He must also complete missions for other people to get items and the Evil Pig Bags. Some side-missions are purely for fun and irrelevant to the main storyline.