A revolutionary augmented reality game from Google that pre-dated Pokemon Go. Similar in design players traverse the real world while trying to capture points of interest.
Pro Enveloping real-world gameplay where the environment is part of the game itself
Ingress is an augmented reality game, so you have to move around the real world to progress in the game, with all that it entails - weather, time of day, city density, etc. The game will follow your movement through your devices' GPS, meaning it works in real time and considers all of the surrounding environment. This makes for a situation that feels all that more real due to traveling in the real world.
Pro Great for exploration and physical activity thanks to how much the game asks the user to travel around
Ingress will get you out and about, walk, bike, drive, swim, float or otherwise. You will notice more of your surroundings, more artwork and interesting places. You will explore areas to find potential new points of interest. It will also get you fitter in the meantime.
Pro Helps teach cryptography principles through the gameplay
Niantic posts daily storyline updates containing passcodes solvable with common cryptographic principles for in-game items. Loads of fun, helps you get gear, and lets you learn a thing or two about classical crypto and encodings.
Pro Huge organized events where you can meet up with like minded people
Con Congested areas are already dominated
It's an extremely fun concept, walking around and building up an affinity with local nodes to you. However, the fun comes to an abrupt stop when a wandering high-level player, in one visit, levels your affinity and puts you in a position where you have no hope of affecting their control. The long-term and serious players leave new players with very little recourse. Completely kills the fun. Though if left untended the whole area will be neutral again in around 7 days. There is also a way to gain Experience (AP) off enemy portals.
While being a problem it does appear to be an isolated issue that can be rectified by working in groups. Even when that is not possible there should still be enough density of portals to allow low-level players to achieve higher levels that then can affect most portals.