UPDATE #6
Well, this time it took us a little bit longer than week, but the last modifications to the game as to be able to integrate a first version of the coop mode, were harder than initially we assumed. The main complexity was with the need to cope with the players selecting which are the characters they would like to integrate, plus some of the core functions that had several dependencies that were not working correctly when having the two players controlled simultaneously. We have also performed some other slight modifications in the RPG mode of the game, as to bring it closer to the genre by making more visual the gain of experience that the player is having while defeating enemies, and at the same time depicting how much remains to upgrade the life/experience/energy ( in UDD all is depicted by the paper bar). Added:
The coop mode. Yes Finally the coop mode as a lot of players asked us, and that as promised, we have finally added to the game. We had to make some choices on how to set it up, and we have decided to go with a horizontal slit screen, as it allows for a more complete side view of the game level, which in UDD is critic. We have also decided to implement some new menus to allow the players to select who is Player One and Player Two and who controls each of the characters. The changes needed to make it work ( and it is still buggy) where complex, due to some of the mechanisms that we had implemented for the single player and specifically for the performance, like the level streaming, which had to modify to cope which characters that will now move separately when playing cooperatively. We are thinking also on the new possibilities of the mode by itself as to see if it can raise even more the fun level.
-Experience Increase Visual Effect. As we commented in the descriptions of the game, one of the genres that we have blended in UDD, is the ARPG, and while playing the game over the last weeks to stabilize it and remove bugs, we have seen that we were missing a clearer indicator to the player, that his experience/energy was being raised while defeating the enemies or solving puzzles, and that after a certain level was reached, increase the level of the paper par, which allow to call more origamis or make them more powerfull. We have add a visual indicator in the Star of the game UI; that will be surrounded by a Blue Glow showing the current level of experience toward increase the life.
-Roll Animation. With the same reasoning, and to increase the combat skills of Ryuu, we have added a roll animation, that allows to break a part from melees attacks with several enemies without taking too much injuries.
-Interactive elements of the environment. To increase the sense of immersion in the game, we have added some interactive elements that will will react to the player movement or attack. We are still testing the possibilities and for now we have add, some bamboos and grass. Fixed: -Noria Animation- The Noria in the Princess side, wasn´t rotating when blocking the path of the princess. -Parallax Bushes assigned to the wrong dimensions, -Jump frame speed dependency. We thought that we had solved this problem, but apparently from some feedback that we have received,not yet totally, so we have been making some more adjustments as to be as consistent as possible.
-Stealth paper consumption. We have also detected that the Stealth ability from Keiko was not consuming any paper. So we have fixed as to deplete the level of life based on the usage of the character special skills. As well as many other small bugs... And yes off course, Yet Another Performance. As always, performance is at the heart of our work, we have been improving the streaming mechanism that will disable all of the objects not visible, and now split per character as each character will move separately. As always any feedback on the discussion board or by email is greatly welcomed as it allows us to keep improving the game and cleaning it from bugs that sometimes we were not able to spot correctly, or to check on fixes that failed to solve them. Also we are open to suggestions or requests that could help us make the game even better. Upside-Down Forums Thanks for playing our game and  Stay tuned...