Upgrade games are not the most challenging of the online game options, but they are hands down some of the most fun that you can find on the internet. The trick is to move up through the levels as fast as you can so that you can sit back and enjoy the silliness.
Most of these games have a ridiculous theme. They tend to be designed more to lighten your mood and make you laugh than anything else. Many are played with only a few buttons because the goal is to upgrade the equipment you use to get more points rather than relying on any sort of real skill. Most do require some reflex but not too much. The point of these games is to earn credits by completing a task based on the theme and equipment and then use those credits to upgrade your equipment. In turn you make even more credits for bigger upgrades.
Upgrade games are almost always side-scrollers and usually come in one of two types. There are the cannon style and the fighting, usually shooting, style. The object of a cannon style is to fire an object as far as you can, the farther you make it, the more credits you earn. There are usually objects set along the course that either help or hinder your progress. You can use your credits to upgrade the power of your cannon and also to add the frequency of helpful objects along the length of the course. In the fighting style games the object is to take out enemies. The more you kill, the better your credit count. In these versions you use the credits to by progressively more powerful weapons, health and shields.
Upgrade games come in a variety of themes that vary to fit a number of preferences. Although they all contain some manner of violence, some are more traditional violence while others are more suitable for specific maturity groups. For instance, the difference of kicking your boss out of a sky-rise building versus firing a cat out of a cannon. There are options for everybody.