WoP 1.2 used to have a Singleplayer button on the main menu, however, if one were to press it, it would display an error saying "Singleplayer is not implemented yet!" There was a Singleplayer mode in the works before WoP 1.5, however the team had too many ideas and cancelled their work. There is no way to play the Singleplayer mode nowadays, nor was there ever. The only evidence is a video released by ENTE himself and a post from Kai-Li in the official WoP website.
The Story Edit
The story of the cancelled Singleplayer is as follows:
PadMan returns home one day to find that PadGirl has been kidnapped by the evil Dr.Pad (Who is also in the same building as PadMan). PadMan then must save PadGirl by going through a portal and into a virtual dimension where he is mouse-size, and has to fight against certain enemies, until he finds the right cords of Dr.Pad. (Pretty much bot-play in the regular WoP maps)
The team had planned many new gametypes, maps and even weapons and characters for the Singleplayer mode, but as mentioned above, the Singleplayer was never finished. Hence the "Create" and "Join" buttons in the WoP 1.5 menu, instead of the old "Multi" and "Single" buttons in the WoP 1.2 menu.
The PadBlock map Edit
It is confirmed that the map where the player starts their journey is created by ENTE (It's on his page, ENTE's Welt)
It's an apartment complex where PadMan and PadGirl live on the top floor. On all the other floors there are doors with the names of the WoP team members.
The elevator in the middle of the stairs appears to be broken, so PadMan has to take the stairs.
The name "PadBlock" is fan-made/unofficial.
Sprinting feature Edit
The video of the Singleplayer mode shows a feature that is not in WoP. Apart from regular running, the player can also sprint by pressing a certain key.
The Video Edit
Here's the video of the Cancelled Singleplayer uploaded by ENTE: