Before noting that I said I do not recommend this, please understand that it's not bad.
With this confusing statement out of the way, let's get started. Bientôt l'été isn't a game. It's an artistic piece, and this needs to be understood. From what I could gather, the goal of it was to demonstrate how people can communicate, even if limited by language, actions, or possible phrases (as seen by the chess board in-game). However, this requires that someone somewhere is playing at the same time you are, unless you want to talk to an AI. It's a beautiful experience when it works well, but this is so rare I can't recommend a purchase at any time other than during a sale. Due to the game's artistic goal and nature, it was heavily slammed upon release, driving away potential players. Without a community waiting for another person to chat with, more people slammed the game for not having a community. This is Bientôt l'été's biggest problem, without players it simply cannot achieve the desired effect.
For this reason I suggest buying this when it's on sale. More players are likely to be experimenting with it at the same time as you, and you're more likely to see the beauty of limited conversation with a complete stranger.