Play the tutorial mission. That's all you need to play before you know whether it'll be worth giving up on a game or not entirely.
If you think it has potential, play the first 1-3 missions, and see. If that potential turns out to be smoke and mirrors, drop it.
If you don't, drop it there and then.
An important thing in game design is nailing the intro. The idea is to put all of why your game is awesome into the first 5 minutes, or, more reasonably the tutorial, as most players will make up their mind about a game pretty quickly, and you want to hook them in and leave a lasting impression. There are a lot of ways to do this; big setpieces, an interesting mystery to solve, awesome mechanics that the player wants to keep experiencing.
If, in the tutorial mission [Or I guess the first mission if the tutorial is actually utter trash; so many games don't know how to make a good tutorial], nothing grabs you at all... Either the game is poorly designed, and you're probably going to trudge through it and not really enjoy it, or its hook just isn't something that appeals to you.
If you find it amazing... Keep playing, eventually they'll get you back to that point, after dropping you down to a more boring period for a bit.
If you find it interesting, but aren't sure - first one to three missions. See if the issues you had with it were just them trying too hard to cram everything into the first five minutes. If after the first few missions its just dragging on though, and its unenjoyable - drop it. Its obviously not worth it to reach the fun that was hinted at in the tutorial.
It does depend on the genre of game though, and its budget, and a bunch of other things. One example that for me immediately comes to mind to counteract this is Sunless Sea. Its big hook is probably its story, which it can get you with in the first 5 minutes, but I also enjoy the gameplay and resource management - but the tutorial is literally a wall of text that's painful to move through, and so you'll finish it and not really know how to play. That's half the hook, discovering everything in the game, but you don't know where anything is, haven't the slightest clue of how to make money efficiently, and it can be very offputting because of this. And this is reflected in its reviews; Most people's complaints about it is the grind, and the need to repeat all these painfully slow trading runs to be able to earn anything. In reality, that's the slowest way to earn money, and its a lot like Dwarf Fortress in that if you play the safe way you'll not have a ton of fun, and you'll progress slowly. If you throw caution to the wind, yeah, you'll probably die [Though in SS its pretty easy to avoid that... Usually], but you'll progress much faster, and you'll experience the fun part of the game and learn how to survive AND enjoy yourself at the same time. But the game doesn't really push you to do that. It drops a couple of hints about exploring, but thanks to how strong most of the enemies are, it feels like you shouldn't because you'll need to fight them [Don't, just run], and you know you won't win, so you need to grind until you can.
The tutorial and first hour or two are terrible, until you learn what you're doing and THE SUN THE SUN THE SUN THE SUN THE SUN... Sorry. But things become interesting later.
Its an interesting case for researching and knowing about the game you're going to play. Sometimes the game just doesn't explain things to you, and you'll play it 'wrong' before learning that the fun way you wanted to play it in is actually encouraged by the game, rather than blocked by it.
Sadly this isn't the case with Dishonored. You get a bad ending if you kill people, the game almost patronises you for it, but its the more fun way to play after your first life - and in general I'd say, where a lot of the more fun sounding abilities kill enemies, yet you're punished for using them. I ended up dropping it right at the end of the first mission. Thing that really got me was there was no autosave functionallity at all. Die at the very last second of an hour or two long mission? Better be happy to do all of it all over again.
Yeah, you can save manually. My problem with that is the same as its always been; it takes you out of the experience. If you've created this world for me to get immersed in and lose myself in, the last thing you want is me purposefully disengaging from your game so that I'll always think of manually saving because you couldn't implement autosave.
But, yeah, I'm not a fan of the idea of needing to play lots of a game to get to the good bit. I personally will, simply because I have the time and patience, but honestly if a game hasn't got your interest after the tutorial [Provided its not a 'this is the absolute basics' with little to no context styled tutorial], then you're probably not going to enjoy it.
