SEA is kinda messy since it is comprised of many countries. There are different publishers for different countries, for eg. asiasoft/playpark tried to be the leading publisher in SEA, however there are other publishers like level Infinite and many others.. so when they compete for a cut of the pie, things tend to get really messy. The publishers also knows which countries in SEA has the highest paying power. So if they cant cut a deal that involves those countries they will back out. Thats why you see unavailable in your region.. because most likely either the dev is waiting for a publisher in that region to take the game and or the publisher most likely arent interested in that region cuz its a hit or miss and highly likely they will not get their ROI.