If you're into the 2-D side scroller games and you really like old-school Japanese game design, check out Doukutsu Monogatari ("Cave Story"). It's a freeware game (hard to believe, but it's true) that has versions for Mac and Windows. It was originally made in Japanese, but recently there have been English translations available.
I haven't been a big arcade-type 2-D scroller-type gamer for many years, but this one really should be checked out if you haven't seen it before. It's got 80's-style graphics and music, but it's just really well done.
From one web site:
Check it out and download it here.
You have to first download the game, and then the English translator patcher.
The control keys are as follows:
q - inventory
w - map (you have to find it first)
a - previous weapon (first you have to find more than one weapon)
s - next weapon (first you have to find more than one weapon)
z - jump / select / speed up dialogue
x - shoot (first you have to find a gun)
The arrow keys do multiple things, including movement and aiming your weapon. The most important one is the down arrow. It causes you to "interact" with whatever you are standing in front of. If it's a door, you go through the door; if it's a person, you interact with the person; if it's an object, you look at or use the object.
The arrow keys also are used for movement and aiming your weapon. So:
down arrow - go through doors, interact with people/ objects, aim weapon down (only while jumping)
up arrow - aim weapon up
left arrow - go left/aim left
right arrow - go right/aim right
tab - toggles fullscreen (very nice)
One important note is that the Z key is used to make selections, like on the main menu. It's also used to advance dialogue when it pauses. Finally, if you hold down the Z key during dialogue, it speeds up the dialogue.
This is a very cool game. Enjoy!!