Besides adding custom levels, this add-on also includes a .PAK file manager called XPAK as an attempt to promote a more secure method of editing game files. A beta version of THRED, a Quake map editor made by Jim Lowell and John Mavor, is included. THRED was unsupported on the Aftershock disk due to being a pre-public beta release. This editor was HeadGame's secret weapon, while commercialized heavily prior to the release of the commercial add-on, Mavor was paid to not release the editor so that Aftershock for Quake would have a technological advantage over other companies.
There is also a Deluxe Edition with 50 exclusive standalone levels. However, despite being a "deluxe" edition, it only contains those 50 levels and not the three episodes or the THRED editor included in the regular edition.
The main text file for the game includes various tips for the Weapons and Enemies of the game. There is also a small portion dedicated to the most common Console Commands. The text file also manages to compile a complete list of Secrets for the Base Game.
The add-on consists of four main Episodes and a Starting Map. The first three consist of 4-5 levels and is considered the main campaign of the add-on. Only the third episode has a storyline. The fourth episode is very similar to Deathmatch Arena, meaning it it entirely focused on Multiplayer based levels.
- Episode 1: Dark Terror
- Episode 2: Corrupt Mischief
- Episode 3: Descent into Horror
- DEATHMATCH Maps
On top of the main campaign and DEATHMATCH Maps, there is also a collection of standalone maps (levels not considered part of the campaign and intended to be played separate from each other). These are accessible via a DOS or Windows 95 level select screen.
- Glass - An impenetrable wall that allows Monsters and Ranger to see one another, even when on opposite sides of the barrier.
- Leap of Faith - A seemingly dangerous method used to travel across a massive chasm.
- Cannon - A mounted dual Laser Trap turret that can kill Monsters directly in its line of sight when activated by Ranger.
- Exploding Wall - A destructive wall that explodes on contact with a Rocket Launcher.
There was very little reception in regards to this pack. An anonymous reviewer for ComputersandVideoGames states that while many unofficial Add-ons were terrible cash-ins, this one is quite enjoyable and states that the developers knew what they were doing. He compares this pack to Dark Hour, stating that this pack has a much better balance of gameplay even though the levels are quite challenging. His main complaint was that the levels are so large that they might slow down weaker systems. He also mentions the level editor THRED, though mentions that it has a CAD style interface and is therefore rather unintuitive and should be avoided unless the person is really dedicated.
Jake Parr of The Voice was surprised that Aftershock did not just merely hold levels found off the internet, though stated that this pack had some of those as well. He was not a fan of the storyline for the third episode, stating that it was poorly spelled. He felt the guides in general tended to not explain things in a good method, nor did they have good spelling. He also notes that the campaign has no Secret Levels like the base game. He also felt that the level names were contrived. Jake was not a fan of the standalone maps, stating that they were poorly made and lacked exits. He didn't get the point of loading a map, wandering around, getting bored, and exiting. The levels were large, Enemies were just thrown around, and Secrets were lacking. The only thing he found good about the pack was the usage of new textures, which made the brown world of Quake a bit more colorful. He mentioned that the DOS loader was easy enough to use. Overall, he feels the pack has aged badly and is not worth anyone's time.
QuestGate, a community running several dedicated Quake servers, ran Aftershock for Quake for a bit of time on their QuestGate IV server (18.104.22.168) in January of 1997. According to QuestGate, they were the first to host a server dedicated to this commercial add-on. Users were required to modify DMAS01: Basin due to the original file looking for ASDM02, a level that does not exist. The Aftershock Standalone Levels were also limited in the original level launcher due to the inability to play said levels over the internet; this was fixed with a batch file made by QuestGate called Q95as. Two months later, the server had been replaced with a standard vanilla Cooperative server.