Well, let's at least consider why some games are fun and you want to play them more and more...while other games don't hold your attention for 3 minutes.
Two games that I really think get it right are Minecraft and The Amazing Frog. On the surface, these games have absolutely nothing in common. Punching trees to collect wood in one and throwing a rag-doll frog off the top of a parking garage in the other. So what makes them fun?
First, both are immediately playable. There's no complex story you have to sit through. In fact, I don't know that there's a story at all. There doesn't need to be. And there's no tutorial. You just start doing stuff. You pick it up as you go. You have nothing to lose, except your currently mundane existence in which you are not playing these games.
Second, both create environments of open-ended creativity. Obviously in Minecraft you can build yourself houses or roller-coasters or chicken farms or whatever you want. You can play with friends - one of you digging in holes while the other rigs traps for zombies. Or not. You can really do whatever you want. There are no rules. But The Amazing Frog is not all that different. Okay, so it's more about blowing up cars in Swindon than it is about building things, but there aren't really a lot of rules. You get points for falling, but you don't have to care about that. My kids have also turned the game into hide-and-seek, soccer (well maybe football since it's British), and capture the flag (or crown in this case). Sometimes they just bounce in the bounce house. For like 37 minutes! And there's always something unknown on the horizon. None of us have been able to get in that cargo container hanging from the blimp yet, but it fills our imaginations with ways to maybe get there - all of which end with us blowing something up instead. What's up with that crown anyway?
Third, and this one is maybe odd, but neither game is finished. Huh? Really. Minecraft updates all the time. Do you remember how exciting it was to get carrots on fishing poles so you could finally steer pigs? You'd had pigs to ride for months, and that was fun, but now you can steer them! It's like you just got a whole new game! My daughter gets really excited when Minecraft PE updates on her iPod. New stuff! Even if she's already had that stuff in the PC version, it's still exciting. It's like when you were a kid and you loved checking the mailbox every day...some days you would get something and it would be great! Other days you would get nothing but it just made you more excited about the possibility of getting something tomorrow. These "unfinished" games give you the same feelings. Maybe "unfinished" isn't the right word. Maybe the games are complete in their state of constant change. I can't wait to see the next iteration of Amazing Frog...and if you follow Fayju on Twitter you get to see little hints of things to come that make you even more anxious. Will we get a few more stages? New outfits for the frogs? New things to grab and throw? Or whole new game mechanics? No matter what, I'm sure it will be great - and it keeps players coming back for more.
So now I will summarize.
- Stories. Keep them short.
- Rules. Keep them few.
- Updates. Keep them coming.
And that is how you make a great game. In theory, anyway. If we're going to be scientific about it we have to test this theory by making games according to these rules and see if they become awesome.