Glenn's Gases is a Minecraft mod that was first released under the name "Gases - A New Element". The mod was originally based on .jar-patching, but it was later moved to use the Minecraft Forge API because compatibility with other mods was highly requested. The official name was simultaneously changed to "Glenn's Gases". The mod is also often referred to as "Deadly Gases" or "Glenn's Gasses" (which is incorrect, as the plural form of "gas" is "gases").
The goal of Glenn's Gases is to add semi-realistic mining hazards, ways to avoid said hazards, and possible ways to turn the hazards to your advantage. It is therefore a survival-focused mod aimed on changing the player's survival experience.
Glenn's Gases does, of course, add gases. Some appear in gas pockets deep underground, some appear only on certain events, while some appear only in The Nether. Because some gases react with open flames, Glenn's Gases adds gas-proof lanterns. By spending a moderate amount of iron, the player will be able to avoid large-scale gas-related calamities. Some gases can be used for various purposes, but can only be harvested using piping.
Lighting is significantly nerfed for those who take the necessary safety precautions to avoid gas-related catastrophes. By using Torch Lanterns, the player may avoid igniting airborne gas, but it comes at a cost. By using Gas Lanterns, the lighting source is powerful, but will eventually expire. The most useful, permanent, powerful, and gas-proof lighting source is the Glowstone Lantern, but it requires harvesting of Glowstone. It's up to you how you will handle the gases and lighting.