Thanks for the comment. Might need to adjust the difficulty later.
Progress: I reached the last region, but unable to beat the boss. (6/8 23:00)
-I think the difficulty of spade, cube and diamond region is reasonable and much easier than the heart region.
-The last region is crazy...
-If I use a key to open the door at the right in heart region before unlocking spade region, the game cannot be continued due to not enough key. I think it's better to set the last region door automatically unlocked after clearing 4 regions, instead of putting a key door there+2 key monsters in spade.
-Sometimes there is bug when I move to a key, I cannot collect it and I need to restart the game. (Happened twice in spade region)
-Lack of healing method...The cube ice heals not much (seems 0.5 only?) and it almost cannot be obtained after the heart region. If I lose too much HP in the heart region, basically I have to restart.
-Is it necessary for the items to vanish? Even the letter cards will vanish in a few seconds...If there are monsters around, I can only get item with HP traded or forget about the item.
Really like the general design of the game, and the various attack style of monsters.