General game mechanics

Framerule
Like many other NES games, StarTropics does not check to send you to the next level each frame. The game instead checks once every 8 frames whether to send you to the next area.

Fadeouts
When the game sends you to a new area, the first step will be the previous screen will freeze, and then fade to black. The most useful effect of this is that these fadeouts are where framerules actually come into play. For example, loading into a dungeon triggers a fadeout, and leaving the dungeon triggers a fadeout, however room transitions do not use a fadeout, and as such are not controlled by framerules. This means that time can be saved across rooms in a dungeon, but between dungeons is always a multiple of 8 frames.

Score and Score reduction
When a dungeon is completed, a textbox comes up and your score starts counting up. This score is set at the start of a dungeon, and each frame counts up 30 points. Killing a certain number of enemies in each dungeon can reduce this score by single ticks. Due to the framerule system, it is unclear whether or not a full, one frame score reduction saves time, as it affects the framerule after the dungeon is completed. For example, if you finish dungeon 3-1, the countdown time only affects the framerule from the countdown to entering Miracola. As such, in order for score reduction to have any possible effect, each kill must be free (0 wasted movement frames, even to lag). Even one wasted frame across each of the extra kills negates any possible time save, and an entire, close-up yo-yo attack (8 frames) loses 8 times the frames that the entire process might save.