This is a personal, largely spoiler free (or spoiler-vague) review of the fan-made scenario History in the Making, part of the Mythos Deviations collection by The Beard for Arkham Horror the Card Game.
The Mythos Deviations are a collection of scenarios design to be added into the existing official campaigns. History in the Making is designed to be played as part of the The Forgotten Age, after The Boundary Beyond (4th scenario), Heart of the Elders Part 2 (5th scenario), or City of Archives (6th scenario), or as a standalone scenario or side scenario as normal. In History in the Making, the investigators are stuck in a time loop, and need to fight Conquistidors to get to the artifact that can get them out.
On its face, History in the Making has a premise that seems neat, but like it would lead to bad gameplay - you're stuck in a timeloop, and have to go through the same locations multiple times dredging them out from a resetting exploration deck. Doing the same thing over and over again doesn't seem like it should be fun - but the specific mechanics of the scenario actually make it work. How the exploration deck, enemies, and clues all work together ends up making it fit well, with each loop giving new possibilities. You could certainly rush it - but doing so is risky, especially if it involves your characters splitting up - while taking it slow and steady could lead to it being horrifically punishing.
The scenario has its highs and lows, although the final encounter is a little let down by it - the final enemy has a good chunk of health, but is not particularly threatening, and the mechanics for clue-focused characters to interact with him aren't terribly exciting. A rollercoaster of a scenario ends up just beating a beatdown at the end.
With a 29 XP party, I found Lines of Reality just about right - the thing that's going to matter here more than anything else is soak, as there's a lot of incoming damage and horror. The enemies aren't too tough, but taking too long can end up strangling you.
Lines of Reality is a fun scenario that explores a timeline theme in a way that ends up engaging and uses an exploration deck in a new way, and is a good time even if it's ending is a bit flat.
Rewards
Scenario Cost: 2 XP, or 1 XP as part of a The Forgotten Age campaign
Potential XP Gain: 1 (locations) +2 (2x Coatl Warrior or Yithian Observer, in the encounter deck) +1 (Bartolome de Talavera) = 4 XP or 2 XP after cost, or 3 XP if part of a The Forgotten Age campaign
In addition, on scenario success one investigator may choose to add Temporal Fragment to their deck.
More on Mythos Deviations:
Mythos Deviations: Overall
Lines of Reality: Review and Rewards
Pictures at an Exhibition: Review and Rewards
History in the Making: Review and Rewards
Event Horizon: Review and Rewards
The Labours of Hypnos: Review and Rewards
The Wreck of the Albatross: Review and Rewards
Mythos Deviations Investigators