French Past Continuous and Past Habit
L'imparfait is the imperfect tense of the indicative mood. It expresses actions which were happening, repeated, or habits in the past. The imparfait is (more or less) equivalent to the English past continuous, though sometimes it's better translated by the simple past.
J'écoutais de la musique quand il est entré. - I was listening to music when he came in.
L'année dernière, je me levais à 5 heures. - Last year, I got up (every day) / I would get up at 5am.
To emphasize an ongoing action in the past, you can use the expression être en train de + infinitive.
J'étais en train de jouer - I was playing / I was in the middle of playing.