WWII: Clear Sky 41 is a surprisingly rewarding game with slightly more depth than it first appears. The graphics are pretty poor, but they are passable, and you get to shoot down breakable planes with a big gun.
Shoot planes from a fixed position
WWII: Clear Sky 41 puts you in charge of a large gun that you operate in the first person. You shoot through a crosshair. The artillery shells you fire are not affected by gravity or the wind, which makes the game a little too simple, but also removes a lot of frustration and learning. The planes break when you shoot them down. You only have a certain number of shells, which means most of your shots have to hit in order to win the level. You may collect gold bars in the form of points, which you may then spend on upgrades and further shells. The mouse-controls are far too sensitive, but it is possible to turn down your cursor/mouse sensitivity so that you may make your shots. The airplanes are fighters and bombers from WWII, so shooting them down is easy because they are slow, and they break apart like butterflies being hit with a mallet. The targets get stronger as you progress through the levels, but you get to upgrade your artillery so that it doesn't become too difficult.
More than expected from a free game
WWII: Clear Sky 41 is not a great game, and there are plenty of high-quality free games on the market, such as Fallout Shelter and X-Mercs. However, WWII: Clear Sky 41 is far better than your regular cheap-and-nasty free game. The premise alone is enough to carry the player for an hour or two, and the way the shots fly without being affected by gravity is enough to allow players to challenge themselves to faster and more exciting games. You do not have to rely on deep-thinking accuracy, which means you may blaze away once you are comfortable with the controls.