I use impact at least 2 days a week.
Mostly client stuff and bigger projects.
So these are the features i would like to see be a part of impactjs core and why.
Lightning and shadows system.
For me this seams to be the missing feature right now.
Getting this right and easy to work with on a entity level and maybe scale it down ( turn if off) for mobile.
Better Gui/hud system
touch. Gamepad, mouse.
Like the touch button plugin but that support any type of input.
Its tedious to create UI systems and buttons without some extra layers of logic and then need to handle touch and mouse differently.
Physics system
The build in arcade physics are great.
Add support for round shapes or to be able to rotate the collsionbox.
The box2d integration works.
But it would be nice with some more documentation on this.
How do i easily create a chain etc.
maybe even look at P2.js
Screen FXs
So it get the request quite often to develop tinting or blendmodes, blur effects and masking. So these are usually done with the canvas itself and can be a real memory hog. I want to have a official support for this. Maybe even though pixi.js rendering if that is needed.
A good particle system would be nice to have in place.
Tweening
So there are some great tweening plugins out there.
Would be nice to have it as a official part of impact.
SpriteSheets and animations
More support basically, in place animation callbacks.
Animation blending/smoothing.
Or
http://www.goodboydigital.com/pixi-js-spine-animation/
Camera
More built in camera love.
And the really hard part zooming and scaling.
Pause
Just a more robust basic pause function.
Fonts
More text options. There is a lot of plugins for this already.
So most of these stuff can be done with plugins already developed for impactjs
But it would be better if they could be part of the core and make sure they work if/on updates.