When developing toys and games you need to know what the user experience is first and then, if a new mechanism is needed, try to make that user experience happen by designing and making one. Usually, the harder you have to work on the mechanism, the easier it makes it for the user in terms of simplicity.
When creating mechanisms, there's a huge amount of unknowns - you probably know what the toy/game needs to do, but there are so many variables because every piece needs to work together - plus when you change one piece, it can affect all of the others, often requiring them all to change.
To develop new mechanisms requires a certain mindset as you have to constantly just try things, knowing that they'll probably not work the first time - but if you don't try them, you might not be able to progress to a final, working design. It's virtually impossible for your brain to piece together every moving part and imagine every possible consequence of that chosen solution without physically or digitally trying it out.
Everything also needs to fit inside a certain shape and nowadays everything needs to be smaller for cost so parts need to be smaller and tolerances tighter - meaning there's a very small margin of error and everything needs to be tested again and again for reliability.
This can lead to a dangerous mindset where you avoid pushing mechanisms or designs to their limits because of a fear of failure - there are so many moving parts that one break in the chain means the whole design doesn't work but it's important to push through that, try it out and if it doesn't work, fix it.
3D CAD programs are invaluable when creating complex mechanisms as they allow you to move parts in relation to each other so you can see how everything interacts with each other. You can also view cutaways of certain parts to make it easier to think up other solutions and modify parts. 3D printing also allows for rapid design changes and testing, which hopefully means a prototype/product that works better and plays better than something that didn't have so much testing.
It's also important to be mindful of what the toy company can actually produce reliably in production - if it goes to production and is very difficult to manufacture (and quality control is very rarely perfect) then consumers will get a poor user experience and will leave bad reviews - which can kill a product before it starts.
Hopefully this provides a small insight into the mindset and process of creating mechanisms for toys and games.
Creating Unique Toys Ltd