Haxe (the language Heaps uses) was initially written by Nicolas Cannasse, who worked at Motion Twin for a while; not sure if he was part of the team that did Dead Cells. So it's not a big surprise.
Still, that's a big +1 for Heaps/Haxe then Dead Cells runs fantastically.
EDIT: Ah, looking into it more Nicolas also founded Shiro Games who made Evoland, Northgard, etc. So it might just be following him around (not to disparage it, still looks great).
article of gamasutra about the gaming pipeline of dead cells https://www.gamedeveloper.com/production/art-design-deep-div...