Lingopolo is based on the idea of Comprehensible Input presented in an interactive way. Comprehensible Input is basically learning language from hearing (or reading) material which is just a teeny bit above your current level, so that you can understand it, and new words or sentence structures in the material can be learnt indirectly from context.
There are some great websites which take this concept of Comprehensible Input very seriously, by containing videos in the target language from beginner to advanced.
Lingopolo tries to create a more interactive take on the Comprehensible Input idea.
This is the method which the world's leading language organisation, SIL, uses for their staff to learn languages with one-on-one language helpers. SIL are the leading experts on world linguistics. It is SIL who are the authors of the Ethnologue, the definitive guide to the world's languages.
It is an aural method based on the principle of learning increasingly complex comprehensible input.
It is very closely related to Stephen Krashen's Theory of Language Acquisition.