Introduce a short (3-24 hour) daylight period before the start of darkness.
The blank canvas will allow collaboration and competition on short simple entries, improving accessibility and appeal for contest newcomers. Code will be relatively easy to follow in this period, in contrast with the end of twilight. If this period is short enough, ambitious players will not have time to develop a contest-winning algorithm, and will be motivated to hold back until darkness/twilight. This early daylight might be a friendly introduction to the contest for new players.