The combination locks at the end of each sector suck up a lot of time; approximately a third of your run. Luckily, these problems are pre-loaded so they're not random at all. Although how each is seleceted is still unknown (current best guess is a frame rule cycle). They appear to have a uniform distribution of occurring. However, this doesn't mean there isn't strategy involved to save time. If you get a problem wrong, the computer will take some oxygen, explain the problem, and then skip that question. Doing this is faster than waiting for about half of the answers. Linked is the complete list of combination locks and what to do when encountering each. Have this printed out or on a separate monitor to use as a resource. Or just memorize it. https://imgur.com/a/rDBoeP1 CL - Combo Lock, you can ignore this. This is an arbitrary assignment that I use to identify the combination. Equation - This is only the first of two combinations. Usually you only need to see the first number to know which you're on. A1/A2 - The first and second answer to the problem. C - This is the class I've assigned to each. You'll know this immediately since it determines which lock layout is used. T - The time in seconds each lock should take, using the optimal strategy. vG - The time [v]ersus [G]old split, or the time lost compared to the fastest combination lock you could've encountered. **3/4 - This is the action you should do if you have 3/4 or full tank.** W1 is whiff (or intentionally get wrong) the first question, W2 is whiff the second, W12 is whiff both, and S is solve normally. Of course, if your tank is 1/4, then you have to solve it normally. The calculation assumes you select the first possible answer when whiffing. **1/2 - This is the action you should do if you have half a tank** (can only spare one hit). HC - This is the cost in seconds if only have half a tank, instead of 3/4. DC - This is the cost in seconds if you have a depleted tank instead of 3/4. This guide really only applies to the DOS version. Windows version is always faster to just guess the first option if oxygen allows. The questions are the same though and could be used for Windows as well. *How to use this in-game:* 1. Identify the class of combo locks (e.g. Single digits, Tens, Whole numbers, Fractions etc) based on which lock appears. 2. Narrow down possible combination locks by their equations. Most can be determined from the first number. 3. Once the specific combination lock has been identified, use columns **A1**, **A2** and **3/4** or **1/2** to determine what actions you should do.