Oh man, this entire series. I've probably been aware of the Homestar Runner cartoons for at least half my life now so there's already a mild degree of nostalgia here. And Telltale really delivers on the concept; the characters and writing all match well with the cartoons and it's just as funny as ever. I've always liked that comfy spot between "kid humor" and "adult humor" that they found, it doesn't show signs of either's stupidity but keeps the good parts of each, making it humor that basically anyone can enjoy.
As for the game itself, then. It's a competent point-and-click adventure. The only real moon-logic puzzles are for the optional collectibles, while the main storyline is generally easy to progress with only mild experimentation, and usually the plot guides you in the right direction. Plus there's a hint system if you really get stuck, so the game should easily be completable on its own. I used a guide to look up collectibles but little else. It's certainly fun and clever about what you need to do. The minigames in each episode are also all pretty diverse and interesting; they all bear a degree of stylistic suck and aren't too terribly complex nor difficult but they're worth the 15-20 minutes I tended to spend on them, and a nice diversion from the puzzling and slower pace of the main game.
For the episodes themselves; it's not really possible to buy them separate I think? But they're all pretty interesting and unique in their own way. The first episode is very straightforward and vanilla and a good introduction to the series. The second's theme is strong as well as inducing plenty an amusing moment, and also contains my favorite of all the minigames (and really the most content in general). The third is a bit weak on the first half but the second half returns to form (plus the music being played is just... special.) The fourth is more linear than the rest but has an entirely different atmosphere that basically necessitates this; it's probably the funniest out of all the episodes too. The fifth also has a strong theme and provides a satisfying finale for the season. Even if they really all have nothing at all to do with each other, since each episode is, like the cartoons, pretty much standalone.
All in all though I'd highly recommend this for fans of the cartoons and still would consider it worth checking out even if you know nothing about Homestar Runner.