Think of the classic LucasArts and Sierra games. Less action and a hell of a lot more reading than action-adventures, you can expect a tremendous focus on telling a story, developing characters, and solving puzzles. Your wits rather than reflexes will be pushed to the limit in order to steal victory.
Vast worlds, wide casts of characters, weapons and items galore, along with puzzles to solve, not to mention the variety of forms of combat—this genre has something for everyone. Indeed, it really represents a hybidization of other genres, and when done right the sum is greater than the parts.
Fight off the hordes—be they thugs, robots, or even pigs. This is all about dealing with a crap-ton of enemies at once, laying into them up close and personal. If you can, definitely team up with a friend to increase your chances of survival. Picking up weapons is good, too. Knives and lead pipes put the hurt on.
In one corner, the hero of the day, and in the other, some diabolical enemy. Only one-on-one combat will settle the score. Punches are ok, but special moves are essential.
Platformers (16-bit)
Welcome to the most prevalent of genres, so much so that it needs to be divided into two separate efforts. Although how you kill enemies greatly varies from game to game, you'll always be making crucial ascents between different platforms. Well-timed and accurate leaps will get you far.
Coming after a whole bunch more playtesting...
Speed is the name of the game. Stomp on the gas and take the corners as they come, zooming into the horizon. Of course, the emphasis on simulating a real reacing experience is tempered by the limits of hardware. So much the better! Why not add some missiles and koopa shells to the formula as well?
What makes a classic sports game? How do you even begin to grapple with such a difficult question? Do some sports make better games than others in this era?

As a bonus, you'll also be treated to a new (hopefully better) top 10 format.
Character interaction and development reign supreme. You may spend as much talking to townspeople and customizing chracters as you do fighting strange monsters. You won't find the raw action of many other genres, but then again no other genre possesses such deep stories
Once again, everything is based on characters and experience points. The big difference is that you're responsible for massive armies. Identifying the best match-ups and optimal troop deployments is essential to victory. You must recognize diversity and use it to advantage.
A lone spaceship or cute character flying all over the place, fighting for the survival of the planet—or even universe. Memorize enemy patterns, and choose the right power-up for each situation or you're space dust.
Run, jump, and shoot your weapon in whatever direction is necessary to quell the constant stream of aliens, robots, monsters, or even zombies. While jumping may not be required at all, bear in mind that deadfalls are often more fatal than bullets. Fortunately, you can usually team up with a second player.
This covers all strategy games (other than tactical RPGs), including military tactic games, real time strategy ones, god games, and city building ones—basically anything where the emphasis is on managing resources.
How do you use your limited resources to clear the stage? What's the best way to arrange these blocks? Is this the most efficient way through the maze? If you periodically get stumped and your brain gets a work out and you're constantly solving something, chances are you're playing a puzzle game.