Sad to say, but I've never played it, though I'm not opposed to it, as I've heard some surprisingly good things about it.
I feel that's the real draw of these types of lists is that you find out about a lot of cool games you probably missed one way or another. Fynn's list got me to pick up Radiata Historia, though I have yet to start it.
You totally should man, its actually been surprisingly fun going through it. Though I'll warn you that after every entry, you'll probably want to be playing that game.
I doubt Um Jammer Lammy would be on most people's lists, but as I said, I both love quirky Japanese rhythm games, and it was also the game that got me into the genre as well. So it has a special place in my heart despite being a game you could beat in an hour.
I'm not sure if we share the same #1 actually, but I would be pretty confident that both of our #1's are in each other's top tens. Frankly, I feel I have maybe one game in my actual top ten that will sorta surprise most people, unless you really paid attention to my old posts. I don't talk about this particular game like a broken record like the other nine. I'm pretty sure most of my top ten will not surprise anyone, and a few people here could probably list all ten, but perhaps not in the correct order.
I have been thinking of typing a post concerning a few omissions from this list. Games people know I own or have played that I'm sure everyone would imagine being on this list, but didn't for one reason or another.
I'll have the next entry up soonish.