You can’t expect much from the single-deck-of-cards detective games. But even by the standards of the genre, Decktective: Bloody-Red Roses was absolute bottom tier trash.
The game works very much like the Q-System Sherlock games. You have three clue cards in hand. You can say the name of the card but not discuss them in other ways. On your turn you either discard or play one of the cards, then refill your hand. Everyone sees the played cards, nobody sees the discards.
There are three differences: the cards are drawn from the deck in a fixed order, there are some event cards in the deck that get resolved immediately when they are at the top of the deck, and cards can only be played if a there’s at least as many discards as the card’s threshold value.
In theory all of these look like improvements. But since the deck is just as tiny as in Q-System but there’s now space taken up by the event cards, there’s not a lot of agency. And the story has been written by simpletons, for morons. It is not a detective story in any meaningful way. There is one suspect, every bit of evidence points at them, and there are no red herrings. A five year old could solve this “mystery”.
The gimmick of the game is a little 3d diorama that you build out of cards at the start, and that gets modified a couple of times during the game. It is utterly pointless.