Gravitex 2 is a classic gravity-based time waster. You pick a direction and amount of power, and shoot a ball off into space where various orbs' gravitational pull affect its trajectory. The goal is to collect all the green coins and get the yellow ball safely to its goal.

Interestingly, the green coins are not persistent; if you collect one and get the ball to the goal, that coin does not return again if you replay the level. That means that you don't have to come up with a single magic trajectory that will collect every coin in one go, but instead you can tackle a level multiple times in multiple ways to try to conquer it.

The graphics in Gravitex 2 are simple but do the trick, which can also be said for the soundtrack. The game offers both mouse-based control, and keyboard control. Given that this is very much a trial-and-error based game, you'll want to get comfortable with the keyboard controls, though for very tough levels the only way to finely control the settings is to use the mouse.

Gravitex 2 is pretty much a perfect casual game for people who enjoy physics games. You can play it for five minutes on your coffee break, and come back to it for a few minutes on your lunch hour.

Gravity Pods 2 is a physics-inspired game where the goal is to aim and shoot a ball, and have it arrive at the target. To get it there, you are given a number of tools, or pods, that you can place. The most common one is the red gravity pod, but there are also blue repelling pods, and silver bounce pods. As you might expect, the gravity pods pull the ball around them with varying force, depending on how close the ball is to the pod. The repelling pods work in the opposite manner.

The game gives you total freedom with where to place the pods, which is a blessing and a curse; the total freedom means that you're always wondering if you're so close and just need one more tiny adjustment to beat the level, or if your strategy is entirely wrong, and you need to take a totally fresh approach.

The game also has a bit of a running commentary, and a boatload of snarky comments to "encourage" you. I found myself motivated to beat each level just to see what the next comment was.

Downhill Snowboard is a physics game with a human dimension. You play the part of the snowboarder, and your job is to successfully navigate down the hill, while pulling off tricks over the various jumps you encounter along the way.

The game is very similar to side-scrolling car-based games that require you to maneuver over jumps and other obstacles, but in this case you do not have an engine, and must rely on the power of gravity to pull you down the hill.

My favorite part of Download Snowboard is how your character moves on the screen. Though you only have very limited control over his movements, somehow the developer managed to make the snowboarder's body move in a relatively natural way, particularly with how the knees flex when landing from a jump.

As mentioned, the controls in the game are limited; you can lean your snowboarder back and forth, jump, and grab either the front or back of the board while in the air. While the graphics in the game are simple and repetitive, there are a wide variety of courses ranging from shallow and long high-speed courses to steep and short hazard-ridden courses.

Try as I might, I just can't get away from the physics games. There's something so compelling about applying real-world movement to a game, even if sometimes the physics are only approximations of reality.

Collider, the game I'm into currently, does a fairly good job of approximating balls rolling down ramps and chutes, and otherwise reacting to gravity. There are three types of balls in Collider: positively charged balls, negatively charged balls, and neutral balls. The goal of the game is to get all of the positive and negative balls to touch, causing them to explode and disappear.

Complicating matters is that when two similarly-charged balls touch, they combine into a larger ball. Conversely, if a large positive ball touches a smaller negative one, the negative ball disappears, and the larger positive ball shrinks proportionally.

Your only control in Collider is to place the balls on the playing board, but you are limited by the "radiation line", which is at different heights on different levels. Once you choose positions for all of the balls (and you have to place all of them), you can press the Play button and watch the level unfold.

The first few are easy, but the difficulty ramps up fairly quickly. Luckily (for some), solutions are available for any level if you get stuck - just click the I button on at the top-left of the window, and amongst the options is a Show Solution link.