Game Speed is the speed at which your game runs. There are five speed settings to choose from: Slower, Slow, Normal, Fast and Faster. Faster is the default speed for custom and ladder matches. In the campaign, the game speed cannot be altered when playing at Brutal difficulty.
Internally, as well as in the editor, all time-related values are based on Normal speed. Depending on the game speed setting, the game simulation is simply run at different speeds. The table below shows the simulation speed factors of the five game speed settings.
|Game Speed||Speed Factor||Real-Time Seconds in 1 Minute Normal Time|
On Liquipedia, all Legacy of the Void pages use real-time time and speed values corresponding to Faster game speed. All Wings of Liberty and Heart of the Swarm pages assume Normal game speed. This matches the values that one would see in a standard ladder match (Faster game speed) in the respective game versions.
Legacy of the Void
Starting with Legacy of the Void, all time-related values in game show real-time seconds. That includes tooltips, progress bars and the clock above the minimap. This means, that depending on the game speed a Marine may be shown to take 18, 25 or 42 seconds to train.
APM values displayed by the observer and replay interfaces are always based on real-time (or, for replays, what was real-time when the game was played). Replays store the speed at which they were recorded such that playing a replay back at a different speed will make the in-game clock not show real-time.
Before Legacy of the Void
Before Legacy of the Void, all time-related values shown in game were assuming Normal speed, so when playing on Faster, they were incorrect in terms of real-time seconds. For example, the MULE tooltip said that a MULE would last for 90 seconds, but in a standard game on Faster, it would actually only last 65 seconds real-time.
APM was calculated based on Normal time passed. This meant that if you were playing on Faster, it would be calculating your actions per ~43 seconds real-time. Replays would also not store the game speed the game was recorded at.
- Game time is stored as a signed 16-bit integer. This means that when the game timer reaches 215 = 32768 seconds = 9 hours, 6 minutes, 8 seconds (or 6 hours, 30 minutes, 6 seconds of real time on Faster game speed) the game will automatically end as a loss for all players due to an integer overflow error. 
- The game clock will add an hours space on screen when 1 hour of Normal time has elapsed, regardless of whether or not 1 hour of real time has passed.
- Video of double loss error. twitch.tv. January 25th 2019.