Clair Obscur: Expedition 33 contains 5 Gestral Games required for the trophy/achievement Gestral Games. On the Continent there are five side areas named “Gestral Beach” which each include a unique minigame set up by the Gestrals, with a reward for beating each.
Two of the games only involve completing an individual objective, with the other three having different completion levels with different rewards for each level. For the trophy you don’t seem to need to complete the maximum level for these three games, so if you are struggling with this (most likely with #2 Beach Raft Volley) you can complete just the first two levels and miss the final Outfit reward, but still earn the trophy.
For all other collectibles by story order and by type, refer to Clair Obscur: Expedition 33 Collectible Guide.
Gestral Games
Gestral Games are listed in the order they can be encountered and completed through progression of the story. Unfortunately there is no way in-game to know which you have already completed without individually checking each location or checking for the unique rewards some give.
Gestral Game #1: Obstacle Course
Reach the end of the obstacle course and speak with the Gestral on the final platform. Answer “17” to receive two outfit items and complete the game. Using Lune can be helpful as when running she floats above the ground and won’t be affected by bumps on the terrain.
Gestral Game #2: Beach Raft Volley
Use your melee attack to hit the baby Gestrals back at your opponent. There are three opponent difficulties to beat, awarding 1 x Resplendent Chroma Catalyst, Outfit: Swimsuit II for Lune, and Outfit: Swimsuit II for Sciel. Note the slight delay in your melee attack, and it occurring in a cone in front of you so you can attack slightly before the Gestral reaches you to hit it. On the highest difficulty make sure not to spam your attack, as the delay in between when you can melee again is almost the same as the speed the Gestrals are shot at you. If you miss one it is better to take a hit and reset for the next one instead of getting stuck in a loop missing them and losing immediately. You can also turn on Sprint Toggle so that you don’t need to hold the trigger to sprint the entire time.
If you are struggling with the highest difficulty the requirement to “win” all games seems to not require completing the highest level, so you can leave this and complete all other games and miss out on the final Outfit reward but still earn the trophy.
Gestral Game #3: Gestral Ascension
Reach the top of the obstacle course, only going up. Be careful climbing or you’ll fall all the way back down and must start over. When jumping to ledge as long as you hit them straight on your character will typically climb the ledge, so try to hit platforms straight on whenever possible. Once you reach the top you’ll receive Outfit: Swimsuit for Monoco.
Gestral Game #4: Gestral Race
Beat the race in under 38 seconds to receive all rewards. You receive a Resplendent Chroma Catalayst, a Grandiose Chroma Catalyst, and Outfit: Swimsuit II for Verso.
Gestral Game #5: Climbing Wall
No Gestral on the ground to speak to this time, you need to climb to the top of the wall avoiding the flaming orbs coming from above. Try to stick to the middle so you can move left or right when the pairs of orbs descend. If you get hit you are knocked to the bottom and must try again. There is some leeway where if you are in the process of jumping to the side, the orbs won’t hit you if you are moving to an empty spot. Make it to the top and speak with the Grandis to receive Outfit: Swimsuit for Maelle. If you finished all prior games you will also receive the trophy/achievement 
Gestral Games.
That’s all Gestral Games in Clair Obscur Expedition 33. For all other Collectibles check out Clair Obscur: Expedition 33 Collectible Guide.
