Knife Fight has a few issues....
By itself, it's just a much worse
Militia. If it is the only attack on the board; I don't think anyone would ever buy it. You might buy it
Nothing stops you from revealing it multiple times; so you would discard your opponent's entire hand when they play an attack. It should either only hit players with 5 or more cards in hand; or be discarded or set aside when used.
Even on a board with other attacks; there really only seems like 2 options... either the reaction is mean enough that you never buy other attacks because it is on the board (thus also having no reason to buy Knife Fight; it just takes both the other attack and itself out of consideration). Or it's not strong enough to stop opponents from buying the other attack; in which case you just won't buy Knife Fight at all. It's on-play is just too weak to justify buying it.
Loaded With Cash - what happens if you play it as your first Treasure in a turn? As worded it will count the value of the last treasure played at all; which will usually be the one last played by your opponent. But this can be hard to track; and it also slows the game down a lot because your opponent has to be careful to play basic treasures in the right order. If you meant it to only count the current turn; you can say that. I guess that in that case; it just counts as
if it is the first one played. It's too cheap / too good though... it's cheaper than Silver, and will almost always be worth
or more; as long as you don't buy it at the very start of the game. Finally, a formatting issue; the text should not be under a dividing line; things below the dividing line happen at a time other than when you play the card. Just look at cards like
Bank to see how variable-worth treasures are worded/formatted.
Garbage Day also can be revealed any number of times; so you could draw/trash your entire deck.
A House is not a Home should not have the "attack" type. See
Ill-Gotten Gains for a comparison... the problem with giving it the "attack" type is that all it does is cause confusion; people will wonder if they can reveal a Moat when you gain one (they can't; because Moat reacts to players
playing an attack, not gaining one). It's also just way too harsh and swingy. Randomly trashing a Province from other players, while possibly helping a different opponent by trashing an Estate, without any replacement; is just too much.
Micro SD Card - you should remove "if you can't, too bad". It doesn't add anything to the functionality, and makes the card just sound silly.
The wording on
Keep the Light on doesn't make sense. You say to discard a card "for every treasure you want to reuse", but then there's no instructions about actually getting to reuse treasures. I assume that "reuse" means basically play again... you should use existing terminology that has defined meaning in Dominion. Something like: "Return to your buy phase. Discard any number of cards from your hand. For each card discarded this way, play a treasure card that you have in play." That could be interpreted to allow you to re-play the same treasure repeatedly, which I don't think is was you want; so you'll have to tinker with the wording some.
The wording on
Primer Paint - check out
Merchant for how wording should work on something like this. "If you play the color card" is unclear.