Who is Oscar Lake? is a point-and-click adventure game with FMV sequences that aims to teach a foreign language. Several versions are available, both for the language to be learned (e.g. German, Spanish and French), and the learner's mother tongue.

The player assumes the role of a traveller to a foreign country, and is accused of stealing a priceless diamond. The police thinks the player is Oscar Lake, a notorious thief, and only through thorough investigations and interactive conversations can his innocence be proven. All conversations are in the foreign language, and have several options that lead to a different outcome and eventually different endings. The game has over 1200 vocabulary words.

Built-in tools like a dictionary provide help for the player, and it is possible to record voices and listen to native speakers pronounce words and phrases.