Input
It contains the processing device.
Water pressure in real towers is created by the height of the tower above the surface of the earth, and the diameter of the pipe supplying the water to the output. The same should hold true for a model water tower.
A rather simplistic answer is: The keyboard is an input device, and is plugged into the computer tower, and thus is connected to the motherboard and processor, etc. The monitor is an output device and shows the graphical output from the motherboard for the user to see on the screen.
The "tower" part of a computer contains most of the computer. It is the cabinet that contains input and output devices, as well as storage devices. However, collectively speaking, the label of "processing device" would be more accurate. Or you can say it is an I/O and processing device with storage.
Technically it's neither as it's just a shell that houses the devices. However, if you just mean the computer as a whole, then it is of course both because it's made up of input and output devices.
To beat dark creeps in Desktop Tower Defense, you typically need to have towers that have high damage output or special abilities that target the dark creeps specifically. Towers like Asgard towers or Tesla towers are effective against them. You may also need to strategically place your towers to create a maze to slow down the dark creeps and maximize damage output.
Output.
output
no its storage
Output
Output device