Herumon Tower runs in the browser at playdfmc.com and as a Windows client you download from playdfmc.com/download (the Steam build). The client adds Taskbar Mode: a thin strip that keeps autoplay running along your taskbar while the main window is hidden. These screens are from the client; the web build has no TASKBAR MODE plate.
1The TASKBAR MODE plate
Install the client from playdfmc.com/download and sign in - Steam signs you in by itself. In the client the MENU has one extra plate, TASKBAR MODE; click it to drop the game into the strip.
2The T key
T toggles Taskbar Mode from anywhere in the game, and the binding is listed under GAME SETTINGS > CONTROLS beside Toggle Autoplay. The strip shows the floor, the streak and the autoplay state; click it to bring the window back.
Screenshots are taken from the live game by tools/tutorial_shots_b.py (dfmc-client) and regenerated after interface changes. The rules behind each screen: system-client-shell, system-autoplay.