As other people have replied, I think it's fine as long as there's a free version that's also available. Personally, I started playing Mindustry using the free

As other people have replied, I think it's fine as long as there's a free version that's also available. Personally, I started playing Mindustry using the free version. I enjoyed it and started playing it with a friend. Keeping my version up to date was _just_ annoying enough that throwing the developer $6 (USD) to not start each game session with 20 minutes of fiddling with software versions was worth it. I really liked that it's free and open source AND I really appreciated the easier to use option once I decided that I like this particular game. So giving people the option (free & manual, or token payment and Steam makes my life easier) is actually a really nice, appreciated option for players. Or at least, appreciated by this player :)