Marsh of Rahena is ERH+'s first traditional Fan Mission release, though you would not think it based on the level of technical proficiency he displays. Earlier he released a "sandbox mission" called The Arena, where the player can arrange fights among AI among other things.
This mission however, is firmly planted in the horror domain. The protagonist receives word from his relatives who live in a fort that due to some unfortunate "urban planning" has become a festering swampland, where nobody travels through anymore. As we go to visit our family we start out by trudging through a large, dark and foggy swamp area and must find the enormous aforementioned fort, as well as find a way in. What follows is the slow realization that your relatives are not what they seem, and their home has become dilapidated, haunted and overrun with vermin. The rest of the plot should probably remain unsaid to avoid any spoilers.
What I can say is that the fort in particular is incredibly detailed in it's architecture and the atmosphere of a haunted abandoned swamp fortress is nailed to a T. The fact that the only source of light you have is a physical lantern that you need to carry around with you further solidifies the tense and creepy atmosphere. Unfortunately however, this is where the pros end and the cons take on.
As previously stated, the main lighting mechanic of carrying a lantern with you physically does contribute to the atmosphere, but it becomes incredibly taxing in the long run since the mission will likely take several hours to complete(!!). This mechanic would be excellent in a shorter mission, or if an alternative was added later on in the mission, but as it stands it is at the very least incredibly frustrating. This is further compounded by the fact that most of the mission boils down to a drawn out, elaborate key hunt in a very confusing and circular environment.
The story is mostly fed to the player through readables scattered throughout the mission, and unfortunately they don't add to the immersion and tone of the mission. They are riddled with poor grammar and sometimes campy humor, as is most of the written text in the mission. This at times also makes it very hard to know what to do to make progress in the mission.
The enemies that the player will encounter, while novel, seem a bit cryptic and it's hard to understand how they actually function. That can partially be forgiven since it is a horror mission, but can sometimes feel cheap or frustrating.
These cons, and others that escape me at the moment unfortunately drags this mission down a lot, and makes it more of a chore to play than a pleasure. It really represents a squandered opportunity to make something truly great. Marsh of Rahena could have easily been by far the best horror-themed fan mission of all time if more thought had gone in to flow, clues and story telling. As it stands today, it is at best a visually appealing, horror themed exploration map, and at worst a frustrating test of the player's patience. In my opinion ERH+ should have made this a collaboration project with a more experienced mapper who is good at keeping pacing and gameplay tight, that would have probably made this FM an instant classic!