Most likely this is because Google Play does not handle charging, remitting, and reporting tax on sales to your country's tax authorities. Handling those things, on a per country basis, isn't something we can manage as a small company.

If you want to play on Android, we recommend contacting Google Play support and requesting they handle sales tax for your country. Whenever Google starts doing that, we'll make it available for sale there.

Alternatively, you can play on iOS or Steam, where Apple and Valve handle sales tax for more countries.