Approaches

Constructive and reservoir policies

Build structures that pay off later and survive repeated row rises instead of taking only immediate points.

Retunes an existing policy for survival milestones instead of average score while changing nothing else. The result barely moved.

Look a few moves ahead, take the best column on your own turns, and average over every sampled disc the game might deal.

Instead of judging a column by its average outcome, judge it partly by its worst outcomes, and find that the resulting policy dies much sooner.

Scores visible board traits, adds them together, and plays the highest-valued column.

Clear numbered discs and open covered ones fast enough to keep the board from filling.

Ranks columns partly by their worst imagined futures. Every tested risk setting trails the baseline.

Instead of searching ahead, train a model on past games to judge a board or pick a column, and learn why that kept failing.

Learn the whole spread of how long a game might last, and only leave the safe move when the evidence says so.