Quote from: "GameDevChris"2D adventures made as short to medium-length games and targeted at casual online portals can do quite well, as evidenced by Dave Gilbert's Blackwell series.
However, longer adventure games like Al Emmo are much more risky since they are very expensive to develop and there's no guarantee of making your development costs back, let alone profiting enough to make a livable income. Also, online portals may not want to take larger games on account of their larger filesize (or consumers may not want to download them for the same reason).
Developing shorter adventure games for a casual audience is the safest bet for someone who's starting out.
By the way what is an online portal?
How successful was the blackwell series?