RayHound is currently only at version 0.8, but already demonstrates this beautifully: You are an itsy bitsy cybar space ship (TM), and have no weapons of your own. You can, however, snatch incoming rays within a radius around your ship, at which point, they'll become dangerous to anything that isn't you. Freely moving around a circular arena using the mouse, you alternately dodge and ambush bullets thrown your way, and sling shot them back at their originators (tonnes of identical, circular groups of twisting turrets). Take out a number of enemies at once with a cluster of bent bullets, and you'll earn a 2^n multiplier to that shot. The more skillful the shot, the more you'll earn. Simple, elegant, and encouraging of interesting play.
You're also able to "Boost" by nudging your mouse quickly in a direction. This triggers a bounce-shield around your craft, which knocks any pink bullets in the direction of the nudge. The shots lock onto anything roughly in the same direction. When the bounced, rather than slung shot hits, it earns less points than a sling shot (100, as opposed to 300) as, depending on the number of bullets flying around, and the number of enemy targets, it can be a bit easier to do. It's excellent for cleaning up smaller numbers of enemies quickly, but risky when trying to deal with many different enemies firing at sparodically. Essentially, the sling shot is great for taking on enemies en mass (chuck a swarm of rays their way), while the bounce is better for taking out the last few enemies in a cluster.
There's not a whole lot in this version which I can fault. It's already shaping up very well.
Aesthetically and semiotically everything's fine apart from a few tiny nit-picks.
Interestingly (referring to two posts ago) the lack of a high score board means that I've no real "goals" to aim for, self made or otherwise: The level number passes so fast that if I blink, I miss my progress. The game over screen doesn't even give me enough time to write down my score. I may be achieving new highs, but I'm blind to it, trained as I am, to expect the computer to keep track of it for me. As a result, I end up playing the game almost totally intrinsically, and am probably having a lot more fun because of it.
Certainly I'm not arguing against a high score board, but perhaps this gives us an idea? Maybe it's worth suggesting to the players of our games to play without explicit aims? Perhaps this is what make the open GTA model so wonderful - there's always a chance to just play. Perhaps, to have them toy, rather than game our systems, will see them enjoy themselves more when we DO start to challenge their playfulness and creativity with solid goals? Playing this early version of RayHound makes me feel like I'm playing a Sandboxed version of a typically high-score obsessed shooter. And to its credit, the core gameplay is enguaging enough in of itself that it has me hooked on the intrinsic appeal alone.