I have created a list of such locations based on interviews and news from the Tibia homepage. It is worth noting that in some cases, Knightmare may have had only a minimal impact in creating these locations. Some locations on the list may be debatable such as Darashia and Port Hope. Because so far I have not found very convincing statements on this topic. Obviously, Knightmare was involved in the creation of many more locations, but it's hard to find anything about that. If anyone finds any more locations to add to the list I'd be glad to. I think this list is a good introduction to exploring Knightmare's work.
The Big Old One and Kazordoon
„Dwarven Mountain made by Knightmare in the middle of Tibia”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=12
„With that been done I took up the abandoned Ab'Dendriel and Kazordoon projects. „
Source: https://forums.tibiabr.com/threads/378403-TibiaBR-entrevista-Knightmare?p=5353142#post5353142
Ab’Dendriel
„Elven Town made by Knightmare and Taghor north of the Hills”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=12
„With that been done I took up the abandoned Ab'Dendriel and Kazordoon projects. „
Source: https://forums.tibiabr.com/threads/378403-TibiaBR-entrevista-Knightmare?p=5353142#post5353142
Rookgaard
„Enlargement of the Newbie Island (by Knightmare)”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=23
„For a long time I liked Rookgaard best. I created it from the scratch and it provided a rounded up challenge with an appropriate progression in it's limited content and was nicely balanced.”
Source: https://forums.tibiabr.com/threads/378403-TibiaBR-entrevista-Knightmare?p=5353142#post5353142
Edron
„A new island has been discovered far out in the east. Settlers from Thais have founded the colony Edron there, and the Royal Tibia Line has established a shipping route to and from it. Now this isle waits to be explored. Many thanks to Knightmare who has designed this area.„
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=93
Venore
„Knightmare has designed a great - in a twofold sense: huge and fascinating - area, the city of Venore in the East of the main continent and its surroundings.”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=173
Pits of Inferno
„My submissions sometimes were too ambitious and therefore it took one of my oldest creations, the Pits of Inferno, several years to be properly added into the game.”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=805
Isle of Evil
„Knightmare writes a lot of the great stories as well as larger and challenging questlines like The New Frontier or some crazy ones like Isle of Evil.”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=1189
Zao
„Zao offers players many new challenges and areas to explore but also has a rich background story which was mainly developed by Knightmare”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=1189
Plains of Havoc
„I got accustomed to the tool and finished the first version of the Plains of Havoc”
Source: https://forums.tibiabr.com/threads/378403-TibiaBR-entrevista-Knightmare?p=5353142#post5353142
Ankrahmun Tombs
„When I created the Ankrahmun Tombs I had this Indiana Jones scene in my mind, in which he had to flee from this rolling boulder.”
Source: https://forums.tibiabr.com/threads/378403-TibiaBR-entrevista-Knightmare?p=5353142#post5353142
Ankrahmun
„Knightmare clarifies that when he actually started working for CipSoft and it all went to a more professional level, there were indeed rules he had to follow concerning the content of the game. Everything was checked by Steve, who, according to Knightmare, was not a fan of too exotic experiments. Mixing pirates with fairies, goblins and unicorns, for example, would not have been allowed. Knightmare also remembers that the implementation of Ankrahmun even took quite some persuading on his part.”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=2828
Port Hope
“Every Tibian under the sun knows for a fact that the world of Tibia has been constructed by volunteers in the past, but in the recent years it has completely designed and conceived by Knightmare. Rookgaard, Edron, Darashia, Port Hope and a plethora of other places has been carefully planned by this young German."
Source: http://web.archive.org/web/20060408185538/http://tibianews.net/article.asp?Id=385
Yalahar
„For curiosity's sake though, I remember I had an idea of invaders from a parallel world or dimension who would try to steal magic and Yalahar (formerly known as Dalahar). It begun as an idea of a city under siege by demon hordes with only the city core intact.”
Source: https://www.tibia.com/news/?subtopic=newsarchive&id=2828
„Completely right. It's definitely the biggest city in Tibia. The original idea, the basic spark, derived from the mind of Knightmare who had always wanted to create a really large, round city in state of siege, a bit like the famous historical sieges. The city centre would be the stronghold of the 'good' and the outside ring would form the attack front of the 'evil'. However, again, technical restrictions sometimes prevent us from implementing certain concepts, so the basic idea was changed and developed further by Dens Larika, Knightmare and me until it eventually became what Yalahar is now.”
Source: https://forum.portaltibia.com.br/topic/11420-entrevista-com-chayenne/?tab=comments#comment-142246
Darashia
“Every Tibian under the sun knows for a fact that the world of Tibia has been constructed by volunteers in the past, but in the recent years it has completely designed and conceived by Knightmare. Rookgaard, Edron, Darashia, Port Hope and a plethora of other places has been carefully planned by this young German.”
Source: http://web.archive.org/web/20060408185538/http://tibianews.net/article.asp?Id=385
Carlin
„A. Let me see, I did the plains of havoc first, later on Rookgaard, after that Kazordoon, Ab'Dendriel, The Carlin Sewers, and finally Edron.”
Source: https://web.archive.org/web/20111105153731/http://www.tibianews.net/component/content/article/83-interviews/682-interview-with-cipsoft-knightmare.html
„Then I added NPCs to Carlin, where most of the city had indeed be finished already when I took over.”
Source: https://web.archive.org/web/20201024121121/https://rookie.com.pl/portal/interviews/knightmare
Edron Poison Tower
„Or the poison tower on Edron, it just did not look like I wanted it to look. Thats why I probabl never try my luck at a tibian sphinx as I planned to in the past ;o)”
Source: https://web.archive.org/web/20111105153731/http://www.tibianews.net/component/content/article/83-interviews/682-interview-with-cipsoft-knightmare.html
Thais
„The very first thing I did was to pimp the NPCs in Thais who had really not much to say at all.”
Source: https://web.archive.org/web/20111105153731/http://www.tibianews.net/component/content/article/83-interviews/682-interview-with-cipsoft-knightmare.html
Dawnport
„I had only little input in Dawnport - though I think the name was one of my suggestions, but I don't clearly recall. I vaguely remember helping out by adding an area with trolls and some treasure. Aside from that, I think I did only some minor fixing and tweaking.”
Source: https://web.archive.org/web/20111105153731/http://www.tibianews.net/component/content/article/83-interviews/682-interview-with-cipsoft-knightmare.html
The Hive
„I did not create the Hive and the Hive Born however, those came from the quill of Knightmare.”
Source: https://tibiopedia.pl/forum/t/7132
Liberty Bay
„As far as I can recall, I actually have added most of my major ideas in some form. What was not possible at a certain point found its way into the game later. Some concepts, though, were never realized. I think I already told somewhere, that the original concept for Liberty Bay was a mixup of the pirate theme with European folklore about unicorns and leprechauns. They would have been the creation of the race that was opposing the creators of the Quarra. In the end, it was decided though that we come up with a more conventional setting. That does not mean though that there will never be unicorns and leprechauns.”
Source: https://tibiaevents.com/knightmare