This is a personal, largely spoiler free (or spoiler-vague) review of The Strange Case of Dr. Jekyl and Mr. Hyde custom scenario by The Beard for Arkham Horror the Card Game.
The Strange Case of Dr. Jekyl and Mr. Hyde is a side scenario where the investigators have to help Dr. Jekyl find a cure for his alternate personality while cultists of Yog-Sothoth try to stop them. It's a tricky scenario that threatens players by bogging them down and demanding their actions, and puts the threat of Mr. Hyde front and center.
With a variable doom clock requiring investigators to pass tests of escalating difficulty to buy them more turns, the scenario puts the threat of an early ending front and center. There's a unique feeling, that while there are enemies, none of them feel particularly threatening - but that doesn't mean the scenario is easy. Instead, they add to a constant drip of distraction. Encounter cards that take away actions, cards, and assets bog the investigators down, making every inch of progress made a struggle. This is added to by the scenario's sidequest and XP - most of the victory points are reward are well away from the actual goal of the scenario. With the actual length of the scenario variable, and subject to sudden changes based on how the encounter cards go, these side quests add a lot of tension.
The thematic elements leave a lot to be desired - while both the doctor and hyde are present, neither feel particularly interesting. Jekyl's bonus is so minor to be ignorable, and so while he is present, there's little he does to effect the scenario. Mr. Hyde, meanwhile, ends up feeling more like an annoyance than a threat - he demands your attention, requiring you to spend actions and cards to deal with him, but he never feels particularly dangerous, disruptive, or elusive. It's easy enough to just leave him be a turn or two if you have to, and deal with him when you can. This static feeling for what's meant to be the main focus of the scenario ends up being a bit of a drag - it saps the scenario of what should be its greatest source of flavor. The rest of the mechanics of the scenario are interesting, but generally don't lead to much besides the usual clearing out a location of clues one at a time.
With a 19 XP party, I found The Strange Case of Dr. Jekyl and Mr. Hyde on the challenging side - with the standalone chaos bag making it especially difficult. Due to the fact that there are many tests that need to be completed to win the scenario that have costly penalties if you fail, not covering the -5 and -6 tokens in the standalone bag can be disasterous. This ends up costing a lot in the way of resources that the scenario is constantly eating away at. As a side scenario in a campaign without these tokens, this scenario would be much easier to complete. Investigators who have a high stat that they can pump higher are at an advantage, especially if they're clue-gathering characters. Meanwhile, groups who don't have good willpower or intellect are going to struggle.
None of the mechanics in the scenario are particularly complicated, although there are enough triggers that you need to keep track of things going on in multiple play areas or locations for many of them. As long as players stay aware of what's going on, keeping track of everything shouldn't be too difficult - but awareness needs to be kept for cards that stick around and trigger in the end of the round, or sit next to the agenda until certain actions are taken.
The Strange Case of Dr. Jekyl and Mr. Hyde is a straightforward scenario, but doesn't particularly shine, and ends up lacking a good memorable hook to really pull it all together.
Rewards
Scenario Cost: 2 XP
Potential XP Gain: 3 (locations) +1 (Sinister Chemist) = 4 XP, or 2 XP after its cost
On a success, one player gains the Fundamental Formula. If you complete the side quest and defeat the Sinister Chemist, one player also gains the Duplicitous Drug:
