Fireboy is a small flame, and Watergirl is a drop of water. Together, they have to complete challenges to get through each level of the temple. You can play alone, but it's easier if you have someone else who can control one of the characters so that you can concentrate on areas you should avoid and areas where you are safe to move through until you reach the end of the level. While playing Fireboy and Watergirl 5, you will discover that you can get from one area of the level to another by using a portal system. All you have to do is stand in front of the portal to be transported to the other area.
There are portals of different colors that you have to keep an eye on because each one will lead to a portal of the same color. You will see black, white, blue, and red portals. You also need to avoid the lakes of lava and water. Fireboy can't get in the water, and Watergirl can't get in the lava. There are also lakes of goo that both of them have to avoid.
Try to look to the end of the level so that you can figure out who should go first in the game to flip the switches and push buttons. As you push buttons and activate the switches, you will see platforms move so that you can walk on them. Use the keys on the keyboard to move the characters around and to jump over the areas where you can't walk. You can also jump up to platforms that you can't otherwise reach. Collect as many crystals and diamonds as you can get because they will help you complete the level and help you get boosters that will offer protection. As you progress through the game, there are more crystals to collect. However, it's harder to get across the platforms and areas that are dangerous to both Fireboy and Watergirl.
The sound effects are fun to listen to, especially when the characters laugh or communicate with each other. The graphics are good as well and look like a cartoon that you might watch on television. Some of the controls can be slow to respond. On the other hand, running can be a bit too fast at times, making you miss the lakes and the areas you need to avoid.