I play a lot of Flash games (especially on Kongregate), for two basic reasons. One, they're free. And two, their low budgets and quick development time mean you often encounter innovative ideas that wouldn't function in a big studio release, or even as a dedicated indie game.
At least, that's what I tell myself, as I load up another damn 'Launcher' game and start sending my (pirate/buffalo/monkey/rocket/penguin/nerd/whatever pick one as applicable) hurtling through landscapes full of stuff designed to either impede or increase its progress upward or outward. So I find myself wondering: What, exactly, is so compulsive about this genre of games?
The first Launcher game I ever played was the inexplicably Japanese NANACA(Cross)CRASH!! a weird, Flash-based spin-off of a Japanese game I've only barely ever heard of (I said Japanese twice in that last sentence, because this game is very, very Japanese). The premise is simple: You're a dude. A girl hits you with her bike. AWAY YOU GO! There are people on the ground, some boost you, some slow you down. If you hit them in certain orders, weird special effects (none well explained) occur, usually to your benefit.
First, the game's playtimes are very short - each session takes about a minute, unless you do very well, or very poorly. In each of these sessions, you get a wide array of emotional moments - the giddy speed of the initial launch, the pleasures or disappointments of near-misses or barely-grabbed boosts, the thrill as you catch a last-minute reprieve, the slow decline (or immediate abrupt stop) of lost momentum and the end of the session. It's very much a roller coaster (except, in this case, you can immediately get back on).
Second, the game sits in the sweet spot between luck and player skill. The initial launch is entirely dependent on the player's reflexes, but after that, control is extremely limited. You get 3 "Boosts", where you can knock your airborne character up and give him a little speed, and a slowly recharging down-kick that imparts speed and lets you push him towards the characters on the ground. That's it. The rest of the game is watching your character float along, waiting for the ideal moments to deploy your limited controls. The order of characters on the ground is random (although the player is given a small indicator so that they know which boosts or detriments are coming up), so it's very easy for a lucky player to hit several boosts in a row, massively increasing speed and distance traveled, and for an unlucky player to hit an instant stop. However, the player control means that, when you use one of your limited interventions and it works, the feeling is intoxicating. Essentially, we have a situation where happy outcomes feel like a result of player skill, while negative results feel like bad luck. That's a recipe for players deriving pride from their successes without being too discouraged by their losses, and feeding that positive feeling is a great way to keep people playing.
One thing NANACA(Cross)CRASH!! doesn't have that its descendents almost always do, though, is any kind of progression structure. Every launch starts with the same probabilities of success - you can't upgrade the bike or pay an in-game currency to make the beneficial characters more prevalent. This makes NCC!! ideal as a score game, one where you can post a crowing high score to your friends with no caveats about whichever upgrades you've purchased, or how long you had to play the game to unlock the SUPER BIKE that got you your score - there's only 'skill' (which, see point 2 above). However, it also means that, once you've gotten a score you like, there's no sense of investment in the game, no feeling of sunk costs to pull you back in for another play.
In contrast, let's look at a game I've talked about on here before, Burrito Bison Revenge. BBR (produced by Juicy Beast) shares many design elements with NNC!!, - timing based launching, special units that boost or reduce speed, a limited control scheme prioritizing carefully timed interventions), but adds a few things that really let the game put its hooks in. (An easy way to know when a game 'has' you, and one I'll refer to repeatedly here, is when you have the thought "I'll just play until _____," where _____ is some measure of in-game progression. Once you've started bargaining with yourself for more playtime, you know you're in trouble). The first is an upgrade system, where in-game currency can be spent to enhance various features of your flight (stronger launches, less speed lost from mistakes, more control interventions, and several others). This does two important things: One, it gives the player a small-scale goal to play toward - "I'll stop once I've got enough money for that top speed upgrade" (but of course, you're going to want to TRY OUT the new upgrade, aren't you? And now you're so close to that bounciness upgrade...)- and two, it ensures that the player, regardless of skill level, will do better and better as play continues. Even if the player never gets better at using the rocket slams (the game's limited control scheme), by nature of upgrading their character, they'll go, generally, further and further with every launch. Thus, you avoid the discouraging scenario often found in NANACA, where a great launch can be followed by an abysmally cut-short one; instead, you have a constant, pleasing feeling of (fake) improvement.
A short list of good launchers:
1) NANACA(Cross)CRASH - Weird, and addictive. Feel free to post your best score in the comments here; mine's 10,145.
2) Burrito Bison Revenge - The king of launchers - gorgeous graphics, varied controls, and an expertly machined sense of progression.
3) Learn to Fly 2 - This one offers a great deal more control than the first two, and also has an EXTREMELY CHARMING PENGUIN
4) Into Space 2 - the best of the Vertical Launcher genre, where your goal is to go up, not out. A really, really detailed upgrade system.
There, that should be enough to waste a few of your days.