Bombchu

The Bombchu is a self-propelled variant of the bomb featured in several games in the Legend of Zelda series. The name comes from the fact that it is an explosive ("Bomb") and the fact that it resembles a mouse ("chu" being a Japanese onomatopoeia for the sound a mouse makes). The plural form of Bombchu can be either Bombchu or Bombchus. This mechanical device is not to be confused with the living Real Bombchu.

Ocarina of Time
Making their debut in Ocarina of Time, Bombchu can crawl along walls and deliver explosive power to areas out of reach for regular bombs or other weapons. Though useful, they are not required to progress through the game.

Like Bombs, Link loses a Bombchu whenever he uses one, and must resupply his ammunition of Bombchu to continue using them. Unlike Bombs and most forms of ammunition, Bombchu can be much more difficult to replace, as they never appear from common locations such as broken jars or slain enemies. They can nonetheless be found in several specific locations, including hidden treasure chests in dungeons, or any of the following: Despite the rarity of Bombchu, Link can hold up to 50 of them at a time. He cannot upgrade the maximum amount he can carry, unlike most forms of ammunition in the game.
 * After finding 40 Gold Skulltula Tokens, Link can collect some Bombchu from the fourth son at the House of Skulltula in Kakariko Village.
 * The Bombchu Bowling Alley will give out Bombchu as one of the prizes Link wins if he wins the alley's minigame.
 * There is a Bombchu Shop open at night in the alleyways of Castle Town, although their stock is limited, and each item can only be bought once before selling out.
 * There is a mysterious salesman on a flying carpet in the Haunted Wasteland, just outside Gerudo's Fortress, who sells packs of 10 Bombchu for 200 Rupees. Disregarding the price, this is perhaps the quickest and easiest method to restock Bombchu, once it becomes available.

Majora's Mask
Bombchu appear mostly the same as in Ocarina of Time. However, Majora's Mask also saw the introduction of Real Bombchu, living creatures that resemble Bombchu and might have been the inspiration for the mechanical Bombchu. Although Bombchu are still not found as commonly as other ammunition, they are far easier to acquire in Majora's Mask, thanks largely to the local Bomb Shop of Clock Town, which sells a pack of 10 Bombchu for merely 40 Rupees.

Despite the larger prevalence of Bombchu, Link can now only carry 20 of them at a time, and has no way to increase his maximum capacity.

Oracle Series
In and, Bombchu aesthetically appear similar to previous games, but have a distinctly different function. Instead of traveling in a straight line, the explosive will lock onto one target and follow that target until it impacts and explodes. If no enemy is present, the Bombchu will simply travel forward in a straight line.

Once again, Bombchu are very difficult to find. They can only be obtained in a Linked Game via the Subrosian Secret or the Troy Secret. Once obtained, Syrup will start selling packs of them at the high price of 100 Rupees for five Bombchu.

The Wind Waker
In, Bombchu is the name of the rats carrying bombs, as revealed by the creature's figurine profile. Actual usable Bombchu items, however, cannot be found anywhere in the game.

Twilight Princess
There are no Bombchu by name in. There are, however, Bomblings, which serve a similar purpose. These Bomblings function similarly to Bombchu in that when released, they will running in a straight line, or home in on an enemy if present, then explode on impact. Unlike true Bombchu, they travel at a somewhat slower pace, and cannot climb walls. Like Bombchu, they are relatively expensive and difficult to find, compared to other ammunition.

Phantom Hourglass
In, Bombchu are found in the Goron Temple. They are the only items which can go through small holes in walls. When used, the map goes to the bottom screen and enlarges, and the player must draw the path that they want the Bombchu to take. Link can move around at the same time as the Bombchu. This is required to solve certain puzzles.

Unlike previous games, Bombchu take more time to use. They do not automatically travel in a straight line nor home in on enemies, and travel at a noticeably slower pace. They can nonetheless prove very useful, as they can be used to scout areas ahead of Link, or even attack enemies around corners long before the enemies even notice Link's presence.

This game marks the first in which Bombchu are given their own, specialized Bombchu Bag, as well as the first in which Link can increase his capacity of them. While initially only able to carry 10 of the explosives, acquiring two more Bombchu Bags throughout the game enables him to carry up to 30. Furthermore, this is so far the only game in which Bombchu can be consistently found outside of static locations. While they still appear often in shops, they can also now be found throughout the overworld much like other ammunition, such as inside breakable jars.