Level Design in World Collector
Spoilers ahead, so if you haven't played it yet, check out World Collector.

I had been fiddling around with trying to get "power circuits" into the game for longer than I would care to admit. My self-imposed deadlines for implementing the feature were no match for the thought that with just 10 more minutes I could get them working. Alas, I could not get them working, but rather had to abandon the feature and start designing the levels with one hour until submission.
Fortunately I had some notes made on Friday evening and had at least a vague idea of what I would be doing.
Key goals:
- Introduce concepts gradually with each new world discovered
- Tease with elements you cannot yet reach but will have to return to later
- Have the final goal be teased from the very first world
- Have multiple paths possible too allow for player creativity
- Make sure the player can't get stuck somewhere!
World #1 Panic status: Relaxed

Here the objectives are simple. Firstly we need a new world to collect. During the intro, the first piece is collected simply by running, so this is an opportunity to introduce jumping. Secondly, we tease the final goal of the game with the abstract frog-like creature in an unreachable part of the map. I placed the entrance for this right in a corner to make it easy to avoid accidentally granting access to this room too early when making later worlds.
One final consideration with the first world was to ensure that the player started very centrally for the aesthetics as you drag this first world into the void.
World #2 Panic status: I'm fine

Here I wanted to introduce the spikes to indicate the potential danger of exploring further. I also wanted to, once again, tease a later goal that could not yet be reached. I also wanted to introduce early the fact that you would need to remove rooms in order to proceed, and to do this I made sure there was no option but to go back out to the left into the first room. This was to ensure that I didn't accidentally teach players the idea that it would be possible to proceed simply by adding rooms until too many worlds were complicating it and making it harder to realise that this isn't the case.
World #3 Panic status: Uh... how did it get to that time?

Here I wanted to introduce a little more complexity, including the button and door mechanics. On my first draft I actually had a world piece behind this door, and the moving platform was moving from the start. It wasn't until a later that I came back to it to turn it into a button for the moving platform. I put the moving platform in knowing that I would eventually want it to be used to hit a ceiling button, but I didn't know the details about that yet. I had to be careful not to accidentally allow access to the froggy room.
World 4 Panic status: GO! GO! GO!

I had a lot of things still to fit in, and very little time to do them. I ended up using this room to fit quite a lot in quickly which may otherwise have been split into multiple rooms. Firstly, I made a quick and cheap way to allow access back to the button in world 3. I also wanted to introduce the idea of reusing the same world multiple times, so this is the first room in which it is possible to exist from one side and go straight back in on the other, albeit with some obstacles block your way. I knew I had a moving platform that needed to be useful at some point, so I threw in the ceiling button and the obstacle it allows you to cross. As an afterthought I threw on a crate to make sure players realised these could be moved as soon as they touched it as I was intending to use that mechanic again later to make the final spike jump. Finally, I wanted to make use of that earlier piece that we couldn't yet reach in room 2, which was achieved twith the top left exit.
The spike zone here did not turn out as planned. My intention was that multiple crates could be borrowed from other worlds to get across safely. I carefully placed the room to make it near impossible to jump straight across. There were two big problems with this. The first is that I hadn't implemented the worlds in such a way that their objects could persist when they are deleted, and I certainly didn't have time to implement that now. Such would also lead to the potential of getting the player stuck behind walls of crates. Secondly, I didn't have time to implement checkpoints upon entering a room. I had only implemented the far less forgiving reset back to world 1. This was especially bad thanks to the unintentional long routes required to get around to this point! This meant that dying on these final spikes was not only more likely, but also far more brutal. This remains to be the biggest issue I have with the game as a whole.
In summary this world was very much a case of trying to get as much off the todo list as possible, because I wasn't sure how many more I was going to have time to make!
World 5 Panic status: Emergency mode activate!

At this point I have about 10 minutes remaining, and a quick look over my current tiles reveals that I have no way to complete the game and the path to to complete it would be quite complicated. I also had multiple world tiles in the world which I definitely wasn't going to be able to create. This is when I cut one world and replaced the tile in the right of world 3 with a button to activate the lift, which in hindsight, was a much better idea anyway!
I had to come up with a cheap and easy way to ensure the final piece could be reached and that the lift could be used. The crossroad piece let me do this. To highlight the uniqueness of the room, I decided to give it a totally different style, made entirely out of the grey blocks. So yeah, this room was a bit of a hack, however, I am totally happy with how this turned out. If I'd had an extra hour to make the levels, I probably wouldn't have had this room as I would have had time to design more intricate ones. I'f I'd had two extra hours, then perhaps I actually would have used it, with time to realise such a room makes for a nice unique reward toward the end of the game which unlocks a lot of new potential routes!
World 6 Panic status: AAAAAAHHH!

All I needed now was a way to get back to the froggy-thing. This was a quick and simple path which could go from the first room to the frog as a kind of victory lap.
Conclusion
In conclusion, this didn't exactly go to plan, but with the odd hack and a bit of luck I landed on something that not oly could be played from start to finish, but that I was actually mostly pleased with.
I'm very much looking forward to continuing development on this alongside my current client work. Not only did I have to drop a whole load of features mid-jam, but I have so many ideas for where to take this. Ideas include the aforementioned power lines, mechanical structures which can be joined such as gears, themed collections of worlds, paradigm shifts where the rules of worlds change, e.g. having different shapes, filter doorways which limit which worlds you can use once you cross them.
I would also like to explore the idea of doing more detailed mostly hand-pixelled worlds in one of my usual non-rushed styles such as this:

I'm planning to continue to stream all development at twitch.tv/joecreates and also do a devlog on youtube at https://www.youtube.com/joecreates