Start your idea at the player, start with Aesthetics

These kind of Aesthetics

When coming up with ideas, think about why it would be fun/interesting for the player, not simply how cool it would be.

If you start your idea with a mechanic, it can often be hard to imagine how well it will work. You will need to playtest and iterate to achieve that uncertain fun factor. This can work well, but it’s tricky since you don’t completely know what you are aiming for (other than a cool mechanic). There may have been something fun resulting out of the mechanic, but if you don’t exactly know how it got there, you’re going to have a hard time working towards it. Your best hope is to find something fun and then try to adjust your mechanics to get more out of it.

If you start your idea at aesthetics you’ll go through another process. It will still be hard to come up with mechanics and dynamics to lead to the desired result, but at least you have something to compare it to. You can notice it and iterate towards it early on. This will cause all your mechanics to better support the aesthetics you have in mind, resulting in a better and more focused experience.