This is a personal, largely spoiler free (or spoiler-vague) review of the Colour Out of Oz custom campaign by The Beard for Arkham Horror the Card Game.
In The Colour Out of Oz, the investigators are chasing a meteor that they think holds the deadly colour - and when it crash lands in an island in the middle of the ocean, they find themselves in the land of Oz - and meeting many of the characters of the L. Frank Baum books. The campaign is filled with references, and also new mechanics, story assets, and things to do - with a variety of challenges that get heavily randomized every time, The Colour Out of Oz is an engaging campaign that always has a lot going on.
The story of The Colour Out of Oz has your investigators fighting against the corruptive entity from The Colour Out Of Space, and portrays the colour well - in game mechanics, in flavor text, and even in little things like card formatting. The second half to that thought is the whimsy of Oz is in full force opposing it. The two are an interesting mix, although it does leave it feeling not quite so Arkham. Still, the Oz elements are used well - not just characters, but the large number of fantastical locations are home to all sorts of effects. There's never any particular heavy humor, but the lightness of the characters does end up prominent. It's never quite distracting, but if you're looking for particularly grim and gritty pulp, it isn't here. There's not a lot of reading required, at least - most of the campaign scenarios have short and to the point intros, and while at several points you can check in with the 12 companion, these are all clearly labeled where and how to skip them, so you don't have to go deep into it if you don't want to.
Two new keywords are introduced in the campaign, and both are well tutorialized. Decay acts as a timer, putting horror on a card in play and removing it at the end of each turn, triggering some effect when it's empty. Most of these are treacheries that act as timers, forcing you to get rid of them or flee a location before suffering a nasty effect, but some also cause enemy stats to change if left alive. These effects end up being a big theming of the campaign, and are usually much nastier than most treacheries - but can also be avoided with good play, instead of being as the result of a test. The other is Pervasive, representing an enemy who's at multiple locations at once. This isn't used as much, but is a clean way to handle an effect that's sometimes seen in other campaigns. On the player side, investigators have access to 12 different companions, up to 4 of which can be chosen per scenario, and can be activated to give additional benefits. The main mechanics all focus on things that stick around - locations that become deadly, enemies who turn into hazards, enemies who's presence is felt at multiple locations, and the like.
Difficulty wise, Oz is no push-over (although nowhere near as hard as say The Forgotten Age or The Circle Undone), but it mitigates this through having multiple objectives in several scenarios. The design takes advantage of the fact that the game can throw more at you if you don't have to complete it all, with four different scenarios each having two different acts to complete. For replayability, those four scenarios also are randomized - with the main objective and the encounter deck being in a specific order, but the secondary objective and the locations in a different order each time. These split scenarios all feel a bit similiar due to the necessities of their design, but enough new is going on for each - and the objectives varied enough even if the map layout isn't - that they don't grow dull. The unique campaign mechanics also center the map layouts, forcing you to pay attention to them more than you normally would - you're often having to abandon locations to avoid nasty treacheries on a timer or Pervasive enemies and care heavily about where you are compared to other investigators (sometimes wanting to be close, and sometimes wanting to be far away). Movement and positioning feel more much important - the gameplay never ends up feeling like 'collect clues and move on', and is always engaging you to think about where you need to be.
If there's one downside with the Colour Out of Oz, it's that it gives a lot of things to track. Treacheries and even enemies with Decay will count down every turn and need to be tracked, Pervasive enemies are at locations other than where their card is placed, passive treacheries will care what enemies are in play and what their traits are - and on the player side, companions provide a large number of new options and another card who's status needs to be tracked, as well as multiple acts and tricky locations mean there's always a lot of things to think about. The sheer number of things can be overwhelming at times - and playing through the scenarios requires a good, methodical method to making sure you're doing everything right. Luckily, none of this is ever confusing - despite introducing two new keywords, it's never unclear how these actually function in play.
It's hard to pick a highlight scenario in The Colour Out of Oz, especially due to some of its strongest scenarios being heavily randomized. It starts with its best foot forward - the first scenario carefully introduces how its Pervasive mechanic works, showing you the different ways it might come into play one at a time - and it's a good teaser for things to come, even if that mechanic doesn't come back right away. The next follow-up scenarios are all with randomized goals that will play differently each time due to how they're combined - with the one requiring you to chase around a magical storm and achieve your objective in the places it just left being a particular favorite. The only two scenarios that have anything bad to say about them are the last, although they're not all negatives. Scenario 7's mechanics are a bit on the confusing side - there's simply a lot going on at once, and it can be difficult to take it in. As for the finale, while it's a great one, certain investigator builds might struggle with it if you failed earlier scenarios - while nobody should have problems with contributing, it's just a matter of how much the scenario bites back. The game at least shows these mechanics ahead of time, at least - giving you a chance to shore up any weakness you might have.
Overall, The Colour Out of Oz is a strong campaign that is sure to delight seasoned Arkham players, but demands your full focus.
More on The Colour Out of Oz:
The Colour Out of Oz: Spoiler-Light Review