Another big feature that we added to complete the atmosphere was the use of particle effects to create wind, falling leaves, butterflies and crates breaking. 

Except for the butterflies that are a package from the UE store, all the other particles were made by us. 

https://www.unrealengine.com/marketplace/en-US/product/butterfly-particles  --> link to butterfly package

This little touch that took quite a few hours for each to create, made the game feel much more alive and interactive for the player. 

The checkpoint particle effect activates only when you reach that point, telling the player that is active and if he'll fall out the bounds he will respawn there. 

To create the box breaking we used the same mesh of the crate as an emitter source for the particle effect and set a number of 15 for the spawn count. We made it this way as we felt like was quite unique and different from the classic build-in system for breakables in UE. We also activated collision for the particles that will bounce on the floor before disappearing. The box when broken will have a 0.5 chance of spawning nanoscrews with their unique particle systems, different compared to the single nanoscrew collected around the level. 

Building the wind and leaves PE took a bit longer than the rest as it required a lot of testing and adjusting of the values in the emitter properties. To create the leaves we used the alpha mask of a leaf texture and then applied a range of colors to it.  The leaves are also affected by different strengths of gravity that make that smooth movement like they are carried by the wind.  

For the wind, we made two meshes in Maya and then used a fading material in UE, that changes on an axis during time giving the impression of the wind blowing, and for the rest, we pretty much applied the same steps of the leaves.