A simple puzzle game

January 2022

https://weslord.com/games/duality/

• Arrow keys, WASD, or gamepad to move around
• [ESC] or [CANCEL] to reset the level
• [,] or [.] to skip levels (secret cheat code, shhhh!)

Over the last couple days, I solo jammed out this game. Here are some thoughts (too many thoughts) about that process.

I knew my game was going to be very graphically primitive, so the colors would shoulder the bulk of the responsibility for how the game looks. Before I started coding, I decided to use the colour palette from my favourite text editor colour scheme, Nord.

The colour picker in Unity's editor has a "swatch" feature, which seemed like a perfect place to store my colours. Unfortunately, as of Unity 2020.3.26f, it's pretty clunky. Adding colours through the default colour picker is a bit of a pain, and managing them is even less convenient. Also, the default swatch is not project-specific, but shared for all Unity projects.

I created a new custom swatch and saved it in my project, so that I could check it in to version control. The swatch asset itself also had a slightly better interface for adding colours than via the colour picker itself. Still a little clunky, but an improvement.

There's another limitation here: colours in the swatch are basically just shortcuts to a colour value that you can select in the colour picker, but they are not dynamic at all. Applying the colour to a property does not preserve a relationship with the swatch, so it can't be used for palette swapping.

Luckily my use-case was pretty simple, so this was fine, but even then, the Unity editor would apply the first colour you select in a swatch after opening the colour picker. You can't even click around your different colours to quickly compare options. It's pretty clear this feature isn't a high priority on Unity's radar.

In the end, it did end up saving me a bunch of time. But I'd mostly chalk that up to luck - I happened to be using it in exactly the limited way it was useful for.

I used a vector graphics library called "Shapes" to create all my visual elements. It's a bit expensive, but I bought it a while ago when it was on sale, expecting I'd be doing a lot of vector work someday. It retrospect, though, it wasn't necessary for this project. I built everything out of primitive rectangles, and could have used Unity's built-in 2D rectangle shape instead.

Walls were all instances of a prefab with a static rigidbody, no friction, and a box collider. The collider's shape was automatically synced to the size of the rectangles in OnValidate(), so creating levels was as simple as dropping in a prefab and stretching it to be where I wanted my walls.

This is how I was able to throw together nearly two dozen levels in just a few hours - keeping the tools simple and easy.

I do wish I'd finished coding earlier than I did, to have a bit more time to work on the levels. As it stands, the "harder" levels can easily be beaten by button mashing, rather than deliberate skill or puzzle solving.

I'm using Unity's two dimensional physics for collision detection. And I guess to push blocks around in the later levels (spoiler warning, forget I said anything). But it would be a stretch to describe any other aspect of the game as a "physics simulation". We're fighting against pretty much every other physics feature to get the behaviour we want.

First off, gravity. Can be turned off globally in the 2D Physics settings. Second off, friction. It's pretty important to keep the two blocks in sync, and they get out of sync very fast if one of them slows down every time it rubs against a wall. I made a physics material with zero friction, and applied it to all my prefabs - then later I noticed you can set a default physics material globally in the 2D Physics settings. So that would have been easier. (I set it there too, just in case.)

I made plans for a bunch of cool control modes, but God laughs. You only get one, so you better like it. It's the most interesting one, anyways: the uni- directional link. Oooh! Aahhh!

The way it works is a bit of a hack. Both character objects get the same controller inputs and process them the same. Each of them has their own collider, to stop them from ghosting through their own walls. But the right side character has a bonus child collider that syncs its position to the left side character. This works as a compound collider, so it suffers both constraints.

It works pretty well for the limited scenarios currently in the game, but I wanted a mechanic in later levels where movements are mirrored or rotated around an axis. I don't think it's possible without an overhaul of the movement system.

Also, there are issues with inertia when pushing objects. The right side character will de-synchronize position with left side character if it's the only one pushing a block.

This project was made possible by the following assets:

• Shapes, a vector graphics package by Freya Holmér
• 3270, a font inspired by the IBM 3270 terminal
• Nord, a colour palette for text editors