How does the tax system work for solo indie developers?

So suppose you upload a game on Google Play or Steam and sell like 13 copies only and make 650 rupees as income. Is there tax on even that? And what about if you use Google ads to monetize a mobile game, how does the tax system work for that? Do you need a GST number or smthing?

Also what if you are able to operate without needing a GST number but suddenly you gain popularity and now your income is above a certain threshold ( whatever that threshhold might be ), then what do you do?