Multiple chapters have photo-frame interactables — Cody and May pose together. Hit each one. ~10-12 photo spots throughout the game. Don't skip past them; they require both players to position.
Story moment in the toolshed chapter. Both players need to interact with the toaster sequence. Unmissable on the chapter completion.
Set up the rocket toy in the toy chapter — both players load fuel + position the launcher. Launch the dino. Achievement on the satellite-orbit cinematic.
Co-op train ride section. Both players man different roles (driver + brakeman). Complete the route. Unmissable on the chapter.
Story-locked. Both players must complete the entire campaign together. Unmissable on completion.
Carnival chapter has a daredevil stunt act mini-segment. Both players coordinate trick movements. Survive the full performance for the achievement.
Story-tied. The infamous piggy-bank scene (don't read too much into it). Both players work together to break it. Unmissable on the chapter progression.
Mid-game shrinking chapter (Cody and May get tiny). Find a hidden relaxation cave at the base of a tree root. Both players sit on the meditation pillows for the achievement.
Mid-game toy room chapter has caged plastic dinosaurs. Free them by triggering the cooperative cage mechanism. Story-incidental but easy to miss if you rush.
Mid-game art chapter has a painting both players contribute to. Finish the canvas. Unmissable; the painting becomes the chapter's centrepiece.
Pirate-themed chapter where one player captains the ship. Complete the full sea-voyage sequence. Unmissable on story progression.
Late-game meditation prop. Both players use the point simultaneously and remain still for the meditation cycle. Achievement on completion.
Story-tied. During Rose's appearance, the stuffed elephant gets lost. Track it down through the chapter. Easy to miss if you rush through.
Magnet chapter has a triangulated puzzle requiring both players to position magnets at three vertices simultaneously. Coordinate the placement; the formation glows when correct.
The Helltower is a vertical platforming gauntlet. Both players must reach the top with zero deaths. Practice the section solo first to know the patterns; one bad jump fails it.
Aquatic section has fish that swim near you. Throw food pellets at them by interacting with the dispensers. Cute mini-interaction. Unmissable if you explore.
Both players pick extreme dialogue options during the therapy / argument sequences. The emotional swing triggers the achievement. Story-incidental.
A specific plastic-dinosaur prop becomes briefly edible during a transformation sequence. Both players interact at the right time. Achievement on the consumption.
In the garden / nature chapter, a radio antenna can be tuned by both players adjusting in sync. Find the exact frequency by working together. Wiki has the frequency code.
Minigames are golden boxes scattered through every level. Both players must touch them. Many are off the main path. Wiki has a chapter-by-chapter checklist. Easy to miss; backtrack via chapter select.
