My colleague, @Miss_Dholakia invited me to join her grade 4 class to play the product game. The game is like Connect 4, except that students have to multiply two numbers in order to place a marker on the square with the product of those numbers. There are detailed instructions here. You can also try the online version here.
This is a great example of a “low floor-high ceiling task” in the sense thatit is engaging and challenging for students at different ability levels. Students who need practice multiplying single-digit numbers get plenty of practice in this game. They could even use a calculator or multiplication chart for support as they get started. Students who are already comfortable with multiplication can start thinking in terms of factors and common factors in order to increase their chance of winning the game (or preventing their opponent from winning).
Case in point: I was beaten by a grade 4 student even though I have been teaching math longer than she has been alive!