I have now played 2 games of Black Angel; I have also played Troyes 4 times, all in the past year. I would like to do a comparison of the two games for those who have perhaps played and enjoyed Troyes and would like a rundown of how the two games differ, as clearly they are siblings.
TL;DR
The game state in Black Angel is easier to read because the game has 3 single-use currencies (ships, resources, debris) and one multi-use currency (robots).
Black Angel has a lot more going on in terms of upkeep/fiddliness.
The end of game timer is harder to get a read on in Black Angel as the game moves forward in many small irregular steps instead of a few regular steps.
(b) The current score is much more clear: Black angle has a score track whereas Troyes has private scoring tokens. Black angle has face-up end of game scoring tiles that score linearly, whereas Troyes has hidden scoring that scores non-linearly.
Black Angel has a technology tableau which provides a bit of engine building that did not exist in Troyes (outside of banking future actions)
Troyes' core action selection mechanic is more interesting than Black Angel (choosing up to three dice vs. exactly one).
In Black Angel, even though the missions and technology are abstract, the theme feels more integrated into the mechanics.
Edit: After three plays, I can am beginning to feel that the sum of the differences between Black Angel and Troyes result in a game that feels more wide-open. You often feel like you have a number of good options on your turn; Black Angel feels like exploration, whereas Troyes feels like mitigation.
Activities vs. Missions
Troyes: Activities come up randomly, you see only 25% of them each game. Activities may be purchased (with coins) and you get to do the activity the first turn you place a meeple there. They can be selected by all players, but those who come first get victor point bonuses. One you buy-in, you have access to that activity for the remainder of the game, unless you choose to abandon it to reuse that meeple. Some of these are immediate effects, and others give you the potential for stronger actions later in the game. The suits (yellow/white/red) have very different focuses and personalized artwork. Activities each feel very unique.
Black Angel: Players draft missions and hold them in their hands. Those missions are either one time or ongoing. They then play them out onto the conveyor-like space board. The ongoing missions all have immediate effects when activated, but must be activated on a separate turn after playing them out. Most are time-limited (will eventually fall off the board). 349
When they fall off the board they may be worth 2 points at the end of the game (if you attach them to the right scoring tile). One-time missions activate when they fall off of the board, but you do not need to invest any more actions into them.
The suits (yellow/green/grey) are symmetrical feel kind of "samey"; Missions do not even have titles or artwork. Players own missions and gain a benefit from other players using them (for ongoing missions). Missions are limited (only two players can dock ships with them at one time). Missions must be paid for with "ships" as well as robots.
Meeples vs Robots
Troyes: Meeples are drafted with Influence, a common currency that is also used for dice manipulation. Meeples give you access to dice and to activities. Meeples can abandon their posts at any time to be used in a different capacity.
Black Angel: Robots are added through specific actions in the game, choosing to draft more robots via missions or technology activations. Robots are used to gain more dice and to work at missions. Robots in workstations (where they give you more dice) must be moved to the "breakroom" before they can be assigned to missions (this doesn't really happen). Robots in ships may be flown between missions to change what actions you have available.
Dice Manipulation
Troyes: Can flip up to three dice for a high cost, or reroll one at a low cost. Uses a common currency for dice manipulation and drafting new meeples (Influence). Influence can score at the end of the game, but only if the secret scoring card is in play. You can only manipulate your own dice.
Black Angel: A separate currency (debris) is used for dice manipulation. The manipulation is always deterministic (one cube flips one die). This changes a 0 to a 2 or a 1 to a 3. Debris can score at the end of the game if you draft the appropriate scoring tile. Generally, you can only manipulate your own dice. 50