A rotation is the set of players a coach actually uses in a game and the pattern of substitutions that gets them their minutes. A "tight" rotation uses eight or nine players; a long one spreads minutes thinner.
In HoopSim your rotation is the minutes you give each of the 12 depth-chart slots, 240 in total. Subs come in waves through every quarter, paced to each player's minutes; early in the second quarter the bench gets its longest run while one key player stays out as an anchor. Minutes are a target, not a promise: foul trouble, blowouts, hot hands and fatigue move the real numbers, and the Minutes flex setting (Strict, Normal, Loose) decides how tightly the coach sticks to your targets. As a rule of thumb, stars play in the low-to-mid thirties, a real sixth man in the twenties, and a short bench beats a long one. In the playoffs the rotation tightens on its own and slots 11 and 12 sit.
Rulebook: The 240-minute budget. Related: depth chart, sixth man.