The objective of HOURS is to "seize control of time itself to break through waves of foes in this single-player hack and slash with roguelike elements." You start off as the Invader, one of the fourteen Hosts. You get to choose an upgrade before every round (except for the Epilogue). Your main goal is to defeat every enemy without dying. After this onslaught, you must face a Boss. After going through three rounds, you must fight Resident Mind. On his defeat, you walk to a pink block, and the game is over.
Since I have no where else to link this, I'm linking it here. View the status effects that Hosts and Enemies can have here.
Hours consists of 4 Game modes, Weeks (Insanely easy), Hours (Easy), Minutes (Intermediate), Seconds (Hard), and an additional Speedrunning mode, Hourglass