Chimera Squad is not a departure from the series foundation that was formed with Enemy Unknown, nor is it an evolution like War of Chosen. It is something else, an experimental offshoot from the main games that changes the formula without ever risking the other entries. This is great for fans of the series, as the tweaks made in Chimera Squad radically change the way you’ll play compared to any of the other XCOM games.
...
Because Chimera Squad is turn-based in its most fundamental sense. Unlike the other games in the series where you spent your turn moving and using your entire team before the enemies did the same, Chimera Squad has a proper initiative order. If you’ve ever played Dungeons and Dragons or Divinity: Original Sin, for instance, you’ll be acquainted with the principle, but it still feels incredibly fresh in XCOM.
It might appear to be almost the same on the surface, but it completely changes the way you’ll have to deal with each encounter. Your most powerful unit might debate spending their turn finishing off a wounded grunt because it goes next and might be more dangerous than the turret that doesn’t get to fire until the end of the round. Meanwhile, your medic might have to make a clutch shot against the boss that’s about to slice through your entire team because she’s the only one who can react in time.
...
Other than that, Chimera Squad’s biggest frustration is missing crucial, nearly impossible to miss shots, but that rollercoaster ride of tactical planning and desperate adaptation when it all goes wrong is XCOM’s blessing and its curse. And for those not playing on Ironman mode, the option to reset the current room, rather than the whole mission, means you can try again instantly if it all goes completely wrong.
The new features that Chimera Squad experiments with fit perfectly with the franchise, and showcase a smaller, more focused battle system that loses none of the tension of XCOM's trademark strategic planning. New fans can pick up Chimera Squad and get all the skills they need to go and play its predecessor, while veterans can learn to overcome the brand new challenges.