Is it normal to make up card games and play them by myself?

Don't think it's normal. But your ability to do that is admirable.

i made this card game called solitaire!

That actually sounds pretty awesome.

I made up a solitary Manacala game. It was pretty stupid...

Yeah, I've done that. I even kept score! Cards have always been a very big part of my life. I don't think there's ever a point now where I don't have nine or ten decks, but when I was younger and couldn't afford them, I'd make them. Made a chessboard and a Shogi board too.

I often play Magic the Gathering against my other personalities.

I did this a lot as a kid! I never finished them, though.

I once had a idea for a card game that was like yu-gi-oh. Sadly, it was short lived. The game was TOO COMPLICATED and eventually I ended up forgetting about it.

It's normal.

Me too. My favorite game is called "House of Three". It's very hard to explain it to anyone else, so I'm the only one who will ever know how to play.

What kind of games have you made up? Teach me how to play!

Yes. I play chess against myself all the time.