Everyone has their own process, but I think it’s fine to just start with a simple idea that’s not yet a game, jump in, and experiment around, especially if you’re just starting out. I’m not an expert by any means, but I managed to release a small game of my own recently, and all I had at the start was a test where I could knock over a box by throwing a ball. Everything else that eventually became the game were ideas that I had later while playing around and showing it to other people.

By the way, here’s the game for anyone interested: https://store.steampowered.com/app/2792160/SnowDown/

I didn’t expect to see so many replies!

Hey me too! I released my first game on Steam a month ago and by all objective measures it was a flop, but as a hobbyist I’m still proud of it. It honestly did better than I thought for a small niche game that I did a terrible job of marketing, and my one review so far was quite positive so I’ll count that as a small win as I move onwards to the next game.

EDIT: Here’s the game because my reply is getting harder to spot below - https://store.steampowered.com/app/2792160/SnowDown/ - It’s a small Jackbox-inspired party game (using phones as controllers) but with real-time action and physics as you throw snowballs around and destroy structures.