While developing I have been listening to stories by HP Lovecraft. Not just because of the seasons, but because I am trying to get more familiar with his style of terror. I like some horror movie, games, and books, but not ones that go for shock value.
I have been trying to figure out how to best translate themes of madness, insanity, and dread into good game mechanics. Not to make 'Shards of Magic' into a horror game, but to give it some horror aspects for players who delve into more twisted and evil magic. To me horror is a consequence of being evil; using the dark magics of necromancy and corruption. But how to best display that in the action-RPG genre? And more importantly, how to program it in without breaking other things.
As the game designer I am attempting to mess with the player to either give some frustration, or build intrigue; both to incentivize them to keep going. But it is a very fine line between messing with a player's head and pissing a player off. Anything done, I believe, must be done sparingly and with a "light touch".
One suggestion given to me was to have illusionary monsters and objects. Something a player may see or have to deal with at random times. For example at lower levels of using corruption magic a player may see a random shadow monster fleeing away from the viewable area. At higher levels, or using a lot of corruption magic, maybe the player will see a tree blocking their path that is then no longer around after they go all the way back to town. If implemented, how often should these effects happen, and what would cause or suppress them?
There have been games that focus on madness effects like "Eternal Darkness" (a very fun game) that would mess with the player even in the menu system. While I like the style, that is going a bit too far. I see it as a type of breaking the 'Forth wall" that I want to limit as much as possible.
Finally there is the Lovecraftian style of creepiness and terror. I have seen some good Easteregg examples of creepy things in games (GTA heart in the statue of libery and the possessed children in WoW come to mind), and those are great for giving random, often unexplained, lore to the world. I would like a full-on terrifying forest, sewer/dungeon, or graveyard type area that players can go enjoy a great dungeon crawl. While that can be a lot of fun, it still doesn't give the unearthly feeling Lovecraft was able to give through his use of adjectives. Maybe after some time of exploring these areas a world-ending event can be accidentally triggered. However, I will not make Cthulhu or any of the Elder Gods as fight-able monsters; being able to kill (or even fight against) Cthulhu seems silly to me.
My goal is to give the corruption magic the affect of harming the player as much as it allows the player to harm the world. But too often these tit-for-tat scenarios end up being a numbers game for the player.