Ghost Stories is a cooperative game with a horror theme. As a fan of coop games in general and thematic ones in particular, I own and enjoy Arkham Horror, and I thought I'd post some similarities and differences between these two games.
Time:
GS is not such a long game as Arkahm Horror. AH can take hours to play (around 3h for 2 player games, more with more players) and GS takes about an hour for a 2 player game. In both games turns progress quick enough, although in AH turns are more interleaved, with players completing each phase of the turn in order. This could make downtime a bigger problem in GS where turns are completed by each player in order, although usually everyone is very involved in other players' turns, trying to solve each situation and giving recommendations (or asking for help).
Complexity:
AH is also a more complex game rules-wise. Both games, being cooperative, are easy to learn if playing with at least one experienced player that can explain things as the game is played, although GS will be more accessible to casual players. Strategy-wise, both games offer a good challenge, needing good coordination in order for the players to win. In this sense, the cooperation is similar, with players needing to decide what tasks each player will attempt to help each other and solve the problems that arise.
GS is more basic in its choices and actions. It's basically combat or seek help from the villagers. AH has more options and possible tasks, so it seems more complex. Also, randomness takes a bigger role in AH, with events happening often that affect the game and give a bigger sensation of chaos (that fits perfectly with the theme). GS on the other hand, feels more puzzle-like, and it's very tactic. I say puzzle-like because finding the actions that fit together well to solve each problem as it arises feels a bit like solving a puzzle, where each player adds their own piece.
Gameplay:
Even though the games are pretty different in how they actually play, there are some similar elements. Both games use a dice based combat system, although the one in GS is simpler, because players just roll (no stat based combat) and try to get a number of colored dots equal to the strength of the ghost. Players do have some control over the results thanks to the tao markers (that add a colored dot to the result) or their special powers, but all in all, a combat is just a matter of one dice roll. AH has a more involved combat system that uses a more RPG-like, stats based system. It's more an experience, and more thematic, but GS, being more abstract, does help the puzzle-like feeling I mentioned before.
Both games use tokens that can be collected and help the players at a later point: Tao tokens in GS and Clue tokens in AH. 884
Their use is slightly different but the principle is the same. In AH they have more uses as they're also key to seal gates, so players have to think well when to use them for stat rolls (in combat for example). In GS their usage is more straightforward: most of the times, if you need to spend one to kill a ghost, you'll spend it, as that's their only function. But in GS the tokens come in five colors. This helps the cooperative aspect of the game a lot, as players usually have different quantities of each color available so they have to each take on different types of monsters. This "specialization" does change as the game progresses, and gives a very dynamic feeling.
GS is more combat oriented, as the whole game is about resisting the attack of the ghosts and they just keep on coming. The danger of the board being overrun is very real and the players' main task is to keep the invasion under control. In AH, combat is less important (although it still is important). Players also have to keep the board from being overrun but they have to do so in order to accomplish other tasks (especially closing gates). So while in GS all the players will have to combat lots of ghosts, in AH players can divide different tasks between themselves, and some players may play a whole game without taking part on any combat.
Both players use some kind of system where players can get help from different locations. GS uses a simple system where you know exactly what you're getting from each location. There are also fewer locations. This enhances even more the puzzle-like nature of the game. Specific situations can be almost solved (randomness can still twart your plans) by analyzing the available powers on the board and the possible actions of the players. In AH, each location will have a random event that can help or hinder the players. Also, many times, to get the help you have to make a successful roll for one of your character's stats. This makes planning harder, but enhances the RPG-like feeling of the game. 579