I'm taking that as:
Get core requirements done quickly. Hypothetical example:
- Player can move
- Player can shoot
- Enemies can be hit/killed
- Level win/lose conditions in place
And once that's out of the way, you have the rest of the time to improve everything else about those things:
- Player can move, is animated, feels great, momentum causes delay animation when switching movement directions
- Player can shoot, with cool muzzle flash, hit effects, kick-back, camera shake, implement an ammo counter and reload system
- Enemies can be hit/killed, but have a shield so they can't be hit from the front, and have sound effects and animations
- Level win/lose conditions in place, with added fan-fare like celebratory particles and sounds and a reward or xp system.