All blue cards have been tested. I'm seeing a pattern of the back faces of cards not having art.
Geist of the Archives was also missing art.
Imprisoned in the Moon is a surprisingly tricky card. Due to the way the planeswalkers work (they aren't actually supported by the game; we just found a way to approximate them), you can't easily remove the planeswalker type or subtypes. It breaks things, making the game unable to animate the card properly, resulting in not being able to select or use it in any way.
I fixed this by making a couple of functions that let a card tell the planeswalker manager not to run its type changing code on a particular planeswalker, which allows everything else to run normally.
However, there's also
another issue: tokens. The game has the same inability to work with non-creature tokens, except instead of just not displaying them, it outright crashes. So, if a token is enchanted, then its creature type isn't removed. It's instead made unable to attack or block, which is about as close as we can come without just disallowing token enchanting.
There's
yet another problem, though. Basic lands. If a land is basic but has no basic land types, then the game will be unable to animate or interact with it the same way it does for planeswalkers. For this, I just did nothing with it. I just made it not remove land types from basic lands. It doesn't really matter as far as the card's intent goes, anyway. The only reason it can enchant lands is so there's no complex idea about "it becomes a land, and this enchantment can enchant that creature or planeswalker even though it's a land and not a creature or a planeswalker" type info needed. To be honest, I'm not even sure it
should remove basic or island from a normal island. Since it's
becoming a land, I don't think land types would normally be removed.
If you enchant a non-token creature or a non-basic land, it will behave completely as expected. If you enchant a basic land, it gains the ability to tap for 1 colorless mana, but does nothing else. If you enchant a token, the token becomes colorless, gains the land type, and can tap for mana. If you enchant a planeswalker, it becomes a land with the ability to tap for mana, and it loses its planeswalker abilities, but many effects that target or filter for planeswalkers will still include it. You'll probably also be able to attack it... Not sure.
Frankly, the card has so many issues, I'd normally just mark it as impossible if it wasn't for the fact that it's so close to being right and is also such a major part of the set's story (literally the climax).
Curious Homunculus is also a little bugged. Its mana can currently pay for any spells, but I believe it otherwise works. I didn't test the back side's cost reduction because I still need to fix and test the front anyway.
But blue is otherwise done.