The website user 264er_Fan purchased a disk collection from eBay, which had some previously unknown games on it. Six of these come from Mark Lünnemann, a German programmer, who also wrote Pyramid Guy: Crack World, Dead of Night, Diamonds Man, Gallows Man, Sticknadel, Tunnel John.
The rest, making up the total 13 are: Bomb Man, Chicago (Strategy), Der kleine Hobbit, Doppelkopf, Monsterwall, Nono and Planspiel.
All the games can be seen and downloaded following the link below.
Link: Plus/4 World