Casey Alvis, also known as "Altima" or "Altima Mantoid," is a Doom speedrunner in the United States. He holds a few Doom Compet-N records. Currently, he has a collection of Doom, The Ultimate Doom, Doom II: Hell on Earth, and Final Doom (TNT: Evilution and The Plutonia Experiment) playthroughs on YouTube. In these playthroughs, he teaches his viewers how to achieve each of the Doom games' maps attaining 100% kills, 100% secrets, finding the secret exits on certain maps and finding the exits to the super secret maps. Likewise, Casey also gives helpful tips to viewers on how to survive the respective maps (even the most dangerous/difficult maps or portions of them) while preserving health, ammo, or a combination thereof.
He continues to upload videos related to Doom.
Casey will, from time to time, accept challenges from his channel viewers to complete a Doom map with certain conditions or restrictions. Two of his most recent challenge accomplishments include: The Plutonia Experiment, Map 32 - Go 2 It; from a pistol start without using the BFG 9000, and The Plutonia Experiment, Map 31 - Cyberden; from a pistol start without using the rocket launcher.
Near the end of 2011, he began to upload the currently standing Compet-N records to YouTube. He is currently the sole maintainer of the channel.
On December 11, 2013, Casey played through The Ultimate Doom, Doom II: Hell on Earth, and Final Doom and hosted it on Twitch.tv for a 24-hour event celebrating two decades of Doom; he also uploaded this event to YouTube.