Each player controls a frog in a lily pond. Flies wander around overhead, and you jump up and try to eat them. Each fly is worth two points. Two lily pads are the platforms. If you land in the water, your frog will swim back to a pad. Each round lasts three minutes, and as the game goes on, day turns into night. Finally, both frogs jump offscreen, and a firefly drags a "The End" sign to the middle of the screen.
If you leave a frog alone for 15 seconds, the computer will control it. This leads to an Attract Mode, with the computer playing itself. No two games are identical; the frogs and flies are all controlled by some of the best AI ever seen on the 2600.
Frog Bog provides examples of:
- Artificial Brilliance: By 2600 standards, this is as good as it gets. Flies follow realistic semi-random paths, changing direction and speed. They even seem to become aware that you're after them. Computer-controlled frogs can time their jumps right to eat them, doing as well as a novice player.
- Attract Mode: After 15 seconds, the computer will start playing both frogs.
- Bubblegloop Swamp: Inverted. This is a peaceful swamp, with clean blue water, and you are the frogs.
- Color-Coded Multiplayer: On the Intellivision and Atari 2600, one frog is gray and one is red. The Commodore version used green and pink.
- Competitive Multiplayer: Two players competing to catch the most flies.
- Difficulty Levels: The difficulty switches select between a fixed arc and free control for each frog. (The computer always uses the fixed arc.) If both switches are set to free control, the flies are much more variable.
- Instant 180-Degree Turn: Both frogs turn around instantly.
- In-Universe Game Clock: Day turns into night.
- Jump Physics: Hey, they're frogs! Free control allows a lot of variety, depending on which direction you point the controller and for how long.
- Lead the Target: The game's biggest challenge.
- No Plot? No Problem!: No princesses here, just two frogs after their daily meal.
- Palette Swap: The two frogs, and the two kinds of flies - the ones you eat and the firefly at the end.
- Platform Game: Two lily pads are the platforms. Fall off and you land in the water, and lose some time swimming pack to the nearest pad.
- Scoring Points: One point per fly eaten.
- Side View: Gameplay and sprites are entirely in side view. The pond and water lilies are in an elevated side view, giving some perspective.
- Timed Mission: Three minutes.