I think when we were younger it was easier to latch on to one thing and get really obsessed with it. Burn out was never an issue back then.
I agree Darren, I remember finding all the secret rooms in The Legend of Zelda. All of them. Pre-Internet. I had the entire thing mapped out on graph paper. Did the same thing with Metroid.
Nowadays it takes 60 seconds for my computer to start and I'm irked at the time wasted.
Another thing I think affects me is when I play other people's games, see how great they are, and am like "Well...might at well just play that one." This happened with Gunfist, there are just a ton of procedural shooters out there that are 10x better. So you are left with only the joy of creation, turns out it's not enough sometimes.
I find that with card games I can pump them out quicker and easier, lower risk of burn out, but the medium can be a bit limited. Solo play against the system is hard to make interesting, and in doing so you can sacrifice the face to face fun which tabletop games should really foster. You also cannot simply distribute via free download and expect many people to click and play. People have to actually print things out, so that's a barrier to sharing.
So then you think, "Oh, well I'll just take my card game idea into a computer game everyone can play," finding yourself right back where you started. Bogged down.
Also I really want to make a fully realized procedurally generated real time strategy world town/base building tower defense sim where, when you get enough money, you can outfit a hero to go shut down the dungeons that keep spawning monsters to attack your town/base. The hero controls as in a gauntlet-like hack and slash splatterfest. Multiplayer. Online. Invite your friends. Elf needs more residential zones.
You can't really do that in a card game, unless your idea of a good game includes hundreds of pieces, multiple boards and a 24 hour play time...wait...that would awesome...I should make that game...but not many people will print and play something that big...so maybe I'll program it...ENDLESS LOOP CRASH!!!!!!