Answer:
You'll find this game very amusing, because it is not about getting the right or the wrong answer, but being creative.
Here is a small list of typical "uses" that you can find in books and Internet pages about when to use one tense or another:
(1) Imperfect is used with habitual or repeated actions
(2) Preterite is used with actions that happened just once.
(3) Imperfect is used to describe an action that occurred over an unspecified time
(4) Some words and phrases indicate specific time frames, and therefore signal the use of the preterite.
(5) Words and phrases indicate repetitive, vague or non-specific time frames signal the use of the imperfect.
(6) Imperfect is used to talk about an action that was going on in the past simultaneously with another.
(7) Imperfect is used to describe physical, emotional and mental states or conditions.
(8) The conjunction cuando is almost always followed by the preterit tense.
(9) Preterite is used for actions that were part of a chain of events
