what is so rewarding people find in open-ended/survival games that makes them keep on playing them? To me, here are a few: 1.Easter Eggs you may find 2.Game-changing / game-affecting secrets 3.High Score 4.Randomness you may encounter can you add more?
1. The accomplishment of beating my/other peoples records. 2. I don't know how to describe it but something about survival games just really draws me in, I guess the challenge of going as far as you can, and that it keeps getting progressively harder (I love very challenging things).
I do it for Osmiral's reason 1. I am a very competitive person, and trying to beat other peoples' scores really draws me in.
This would be the big reason for me (possibly the only reason). I'm not huge into highscoring, so unless each run (especially the failed runs) is benefiting me in some way, I'll likely just play it a few times and stop. Another one would be the variety of options the player is offered. For example, dual-stick shooters often have pretty shallow gameplay (kiting and shooting over and over). While I really like the genre, I'm unlikely to sink 20+ hours into a DSS that only has a standard highscoring endless mode since each run just becomes the same thing. On the other hand, (some) tower defense games have an interesting mix of different towers, so there are more possibilities to try. Therefore I'd be more likely to play since I could experiment with new builds. Of course, the most obvious thing would be whether or not the game is fun. If it's boring, no amount of anything else is likely going to get me to continue playing.
Depends on the game but I get hooked on being able to continuously build things up, like Tiny Tower or even good ol Sim City... You make something of your own.