Basic control:
[W]
You use W-key, to eject mass. Each mass you eject is only 80% efficient.
(this matters in team play, because if you're feeding your partner via [W] instead of splitting, you lose 20% of the exchange)
If you W, into the little spiky balls (virus) 7 times, the virus will eject another virus in the direction of your Last ejected mass.
This can be used both offensively, or defensively.
[SPACEBAR]
is for splitting. All the balls you currently hold are split in half and shoot forward a bit (unless one of their mass is less than 36 units, very small)
Splitting is 100% efficient...
Basic strategy.
To capture other cells, you must be 25% larger in mass which means 1.12x the radius of the other cell.
To capture other cells via the SPLITTING (hit spacebar), your splitting ball must be 150% larger in mass, which translates to 1.58x the radius of the other cell.