good game but I wonder if there is an alternative ending availlable, besides the normal default ending after night 4?
There is no alternate ending available, sadly. I wish we had more time to actually implement something like that :)
Right now the extra playthroughs are mainly for exploring all the items and for the optional "Speedrun-Mode" (you can enable it in the settings) to do some quick restarts with all the Items enabled.
Early in development we actually wanted the "night-cycle" to be beatable but we scrapped that idea becouse of time and balance problems. We wanted the game to be beatable by anyone without beeing too punishing for mistakes