Periodic Devlog #4

Welcome to part 2 of game design. In Part 1 I talked a little bit about some of the overarching design philosophies in Gearplexed. Today I'm going to get a little more into the technical side of the game design.

Game Design Part 2

What gear ratios to use? How are gear ratios made? How do we keep the game from turning into math homework? If you’ve played Gearplexed, you probably didn’t even give a second thought to these things. However, at the beginning of development, these were all open questions.

Starting with the basics, gear ratios are made when two gears of different sizes are engaged together. The ratio of the gears’ teeth (or more precisely, the effective circumference) determines the gear ratio. For example, if a large gear with 32 teeth is paired with a small gear of 16 teeth, every time the large gear spins once, the small gear spins twice, doubling the speed (and also halving the torque). The linear motion is always conserved though, so if the target gear is the same size as the source gear, it doesn’t matter what sizes of gears are used in between, the source and target will spin at the same speed. When you co-locate those two gears on the same shaft (achieved in Gearplexed by stacking one gear on top of another), they both spin at the same speed, but now the linear motion of the larger gear is double the smaller gear, and any gears engaged with it will inherit that new speed.

Linear motion is conserved through a flat gear train. Stacking gears will change the speed.

Should there be a limit on how many gears we can stack? If not, the risk of making a situation where a gear gets hidden or things become nonsensical is pretty high. I’m a fan of “keep It stupid simple”, so if the minimum number of layers needed to make a gear ratio is two, then that is the total number of layers that should be available to build with. In order to ensure nothing gets hidden under anything else, all gears on the top layer are open-work, and all gears on the bottom layer are solid. Limiting the layers not only makes things easy to keep track of, it also creates an emergent mechanic of space management.

Keeping the math as simple as possible seemed like a good idea. Keeping everything to whole numbers is ideal. Using gear sizes of 1, 2, 3, 4, and 6 means that any speed or torque, so long as it is a multiple of 12 generally yields whole numbers for the resulting speed or torque no matter what combination of gears is used. The size, by the way, is given instead of teeth because the different themes have different numbers of teeth – the sizes are number of teeth on a gear divided by the number of teeth on the smallest gear (which is actually a wheel, but I digress). As a side note, if you observe the artwork closely, the size of the gear is embedded in several features making up the gear, so you can determine a gear’s size at a glance without having to resort to a tool-tip.

Steam post image The artwork for each gear also gives hints to the size.

Now let’s visit an issue that came up mid-development: serial gear ratios. With 5 sizes of gears and wheels, not including 1:1 ratios, there’s 10 unique gear ratios that can be made. A series of 2 gears therefore has 10² or 100 possible ratios. A series of 3 gears yields 10³ or 1,000 possible combinations. Most people can easily discard 70-80% of these through simple observation, but that still leaves a lot of things to try. I made a couple levels that needed 3 ratios in series, and testing a few months later after forgetting the solution made me frustrated enough to delete those levels.

Perhaps there’s a reason there’s so few gear-based puzzle games out there…

Video games can be challenging, but they also should be fun. Serial gear ratios are not fun, they’re math homework (and not even the fun kind of math homework). Gearplexed has plenty of other levers for ramping the difficulty besides gear ratios, so I leaned into those: making levels larger, weaving gears through obstacles, limiting gears, randomized gear offerings, and a form of player driven time-pressure (e.g. ‘Criss-Cross’, level 5-4 or Demo 9). Then there’s my personal favorite, factory levels. Factory levels give a nice mental break from the normal gameplay by eliminating the need to make exacting gear ratios, but still benefiting from them. They also give belts a second in-game purpose. The casual character of Gearplexed enables absurd factory concepts such as making numbers in ‘Numbers Game’ (level 5-8) and powering the sun to grow corn in ‘Corny Crafting’ (level 6-8). There’s still a few serial gear ratios called for, but they’re limited and often built up in steps (such as in ‘Remember These Steps’, level 5-5 or Demo 10) so you know you’re on the right track.

Gearplexed is fundamentally more a game about problem solving than making gear ratios. You won’t have to do any math (unless you want to), and I’m sure you will find levels you love, levels you hate, and levels that make you question the developer’s sanity. You might even learn a little something along the way. If you enjoy playing with gears, you will enjoy playing Gearplexed. This post concludes the core game design devlogs. Thank you for reading!