
Yeah the beginning is a bit rough because apparently the alien is specifically programmed to not leave you alone in the first level or two that it appears. My initial experience was similar but after the first level it got a lot better.
To me the game either works great and you get a legit scary experience or the alien pops out at the wrong time and you have to briskly walk through the rest of the level or die instantly.
Supposedly they are more likely to give you captchas if there is high traffic, like every week when people try to claim their prime free games at the same time. If I get a captcha I just close out and try again later because you never know how many you are going to get.