M79

Overview
The M79 is a powerful one-shot weapon that fires large explosive bullets, capable of instantly killing an opponent. This slow-moving bullet deals area damage as well as extremely high knockback, however it is heavily affected by gravity. The bullet can also be repelled by many of the other weapons in the game. The M79 can also be used to "Rocket Jump" - the process of shooting under oneself to boost them around for better mobility, at the cost of their own health.

With the M79
When you are using the M79, the greatest roadblock you have to face is the bullet sag. In other words, the M79's projectiles are affected by gravity. A lot. To aim correctly, M79 users must fire slightly over the intended line of fire for the bullet to reach enemies, in an arc-style curve. Another thing to keep in mind is that the M79 has very low range - however, the M79 rocket jump ability makes up for that. Use this feature to your advantage for better mobility in a battle. Lastly, remember that your bullets can get very easily neutralized by players with Flamers, Miniguns, Link Guns, etc. Charging headfirst into a fight against one of these weapon users would most likely result in your death instead of theirs.

Against the M79
Firstly, remember that multiple weapons can neutralize the M79's projectiles. Use weapons like the Flamer to render the opponent's bullets useless and easily overpower them. When fighting against M79 users, you also need to account for where their projectile is going. As aforementioned, their bullets travel in a great arclike style which could unexpectedly take you from above, well over your line of fire. At all times, stay alert for any airborne M79 bullets (or even airborne players wielding it, since the M79 user could be rocket jumping around to take you by surprise - though this is uncommon).

Trivia

 * You can indeed kill yourself with the M79 if you rocket jump too much/stand too close to your own bullet when it hits something, as the splash damage will hurt you even though it is your own bullet. This "suicide attribute" is much like other weapons such as the Avenger, RPG, and X75.
 * The M79 is tied for 1st place in least amount of ammo capacity. It ties only with the Barrett and the RPG.
 * In rare cases, M79 bullets do not damage players at all, but still deal knockback.