Your devout and upstanding uncle and aunt probably have nothing but the best intentions for a young boy like you, but being cooped up reading a sermon while the sun is shining and the birds are whistling is hellworthy torture.
How to get out from under your aunt's watchful eyes to enjoy what's left of this wonderful afternoon?
Sunday Afternoon is a very small game if measured by its map. Five rooms total. Two of those rooms however are so chockful of things to examine that they count double at the very least. A lot of souvenirs and books and bric-a-brac, all with a history.
This ties in to the kind of puzzles in the game. Rather than manipulating some machinery, you have to deal with the people keeping you indoors, and the objects in the rooms hold the key. Finding your uncle and aunt's weak spots, their buttons if you will, requires careful attention to their reactions in conversation and a certain knowledge of their habits and character.
While it is (in theory) entirely possible to finish the game successfully in a flawless runthrough, it's actually recommended that you do a fair amount of flailing around and trying unsuccessful actions multiple times. In a framing story flash-forward reminiscent of Spider & Web, the hapless player will discover a bitterweet justification for the unrealistical behaviour that is typical of the protagonist in a text adventure. It's worth taking a moment to let the circumstances of this framing story sink in. Think about what it means for the actual game/story you're playing/reading.
A very clever small escape game with unexpected depth.