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.

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.