Many new 4K projectors these days come with ultra short throw technology, which vastly reduces the distance needed between the projector and the wall or screen surface it's projecting onto.
The laser light module used for this creates crisp images, though it does ramp up the price from a non-laser long-throw model, or even regular 'short throw' which sits somewhere between the two.
Ultra short throw (or 'UST') is certainly a great space-saving measure, keeping your projector in the same position as you might put a TV, and meaning you don't need to install a projector into your ceiling. With UST, people moving around a room are less likely to block images too. These models also pack better built-in audio than other projector types, along with built-in streaming capability for popular apps.