I confirm what hombre_fatal says.
Lucky for us, this game is a passion project, we are not looking for any profitability. Truth is, if we were, we would have had to give up a long time ago. Server/domain costs are split among 6 admins, all development work (code, design, images, admining, moderation etc) is based on volunteer work from passionates.
Though we do have many players who asked to make donations, but we never accept any so far.
The game will ALWAYS remain 100% free with no pay-to-win and no ads.
Donations won't offset the dev time, but can be significant with a few thousand players. I briefly tried two PBBGs recently (idlescape.com + avabur.com) and could see from the chat that both were bringing in at least thousands a month. The former hasn't been around very long, though, and the latter had microtransactions and somewhat cheap dopamine mechanics.