In short, they're talking about games with no replayability like deduction games and legacy games:
[The Martian Investigations] was a lot of fun. It was a cool thing to be able to do. [...] You should download it. [...] I spent about an hour or an hour and a half and even if I bought it for $2, which is full price, I'd would still feel fully satisfied with the game.Here's the download link, if you are yet to check it out.