As far as I understand, Hong Kong has this Offshore Tax Exemption, where your earnings will be tax-exempt as long as you can demonstrate that your earnings are from foreign sources (i.e., offshore sources outside of Hong Kong).
I built a Charades-game [1] for both iOS [2] and Android [3]. Launched last year and just recently got to around 2k a month, some months like December are of course better than let's say September because of holidays like New Year etc.
It took about 10-12 months reaching those numbers, and I'd say we still have lot's of room for improvement. It's also very low maintenance, but highly scalable. What I do is basically localise the game to as many big languages as I can, and then throw some ASO on it and hold my fingers. Haven't spent any dollars at all on the marketing otherwise.
Thanks for the advise, we do have some full screen ads, but use it conservatively. It is always more satisfying getting revenues through in app purchases since it’s a sign that people value what I’ve created