This is a personal, largely spoiler free (or spoiler-vague) review of the Delta Green Convergence fan made scenario by Ash (Mr Dodger) for Arkham Horror the Card Game.
Delta Green Convergence is based on the Delta Green tabletop roleplaying gamere, where investigators are working with the FBI and looking into a bizarre murder happening in a quiet farming town. The setting draws on paranormal conspiracy stories like the X-Files, featuring alien abductions and government conspiracies. The scenario is based on the "Convergence" scenario from the Delta Green roleplaying game, and tries to have a slow build up of mystery and horror, featuring an unraveling conspiracy in just a single scenario - but poor scenario design, bad rules templating, and a lack of balance end up leaving the experience messy, unfun, and frustrating.
The most obvious, damning example of the bad design on Delta Green Convergence is the Green Box location, which has no use beyond giving an action to allow investigators to search through storage units for strange things to use. Once at the location, you need to spend an action, and then draw a token from the chaos bag - and if it's a symbol, you search a 30 card special deck for the first card that matches the token you drew, and then you get to draw it, adding it to your hand. The deck is full of strange items - and also has a number of punishing weaknesses, the worst of which may seriously debilitate your character for the rest of the scenario, if it doesn't outright kill them. This whole mechanic requires sinking loads of actions in for a 35% chance to draw a weird card - and they aren't even worth using, in many cases! The cards have a wide variety of effects that largely underwhelming - like spending 3 actions and 3 resources to search the top 10 cards of your deck for a card to draw, or spending an action to let you commit a card to someone else's test at another location once. The few cards that are worth using are largely just things like high damage weapons. A significant portion of the design of this scenario went towards a side mechanic that just shouldn't be engaged with at all - where it's asking players to spend entire turns worth of actions for little in the way of reward.
The rest of the scenario feels much like the Green Box mechanic. There's little coherency to it, with the encounter deck just being full of a wide smattering of "conspiracy theory" type effects and the story feeling jumbled and confused, even if it does make a decent attempt at having several "jump off" points depending on how far into the conspiracy the investigators delve. The templating on the cards is poor, with encounter cards having both Forced and Revelation effects, and the balance is all over the place. One encounter card is simply a weaker version of Hunting Shadows, having you pass a test to avoid having to drop or a clue or take one horror. Another encounter card has you choose between taking 3 horror or shuffling all assets in your hand and play area back into your deck, AND moving you back to the beginning of the scenario - possibly up to eight locations away from where you were before! How about a card that sticks around and keeps you from investigating, until you pass an Agility 4 test at the end of your turn? The encounter deck is designed for maximum frustration, and is combined with effects that are just unclear throughout the entire scenario - for example, there are several encounter cards that tell you to place clues on them when you discover clues, and then discard the card when you reach a certain amount. It's unclear what happens to these clues - which is important, because there's no way to get more clues on locations in the scenario, and you need a certain number to advance!
Overall, Deltra Green Convergence barely holds up as a playable scenario - and attempting to delve into its mysteries is likely to be a source of frustration and little else.
Rewards
Scenario Cost: No XP cost is listed
Potential XP Gain: 1 (locations) +1 (Protomatter Mass, found after fully investigating the Town Hall) +2 (Spawn of Ubbo-Sathla) +3 (successful scenario resolution) = 7 XP total