TWilight INSanity Mechanics
Begins at 50%. Increases as long as enemies are on the screen. If it reaches 100%, it's an instant game over (Continuing forces you into a Bad Ending). Infection Rate has a major effect on plot events and available choices.
Ratio of how much each partner has been used. Also has an effect on plot events. Certain events will prevent switching characters but usually you can switch at will.
The multiplier is affected by how fast you defeat viruses. The maximum is 4x. This also has a direct effect on eCrystal generation (see below).
Upper Left: eCrystal
Generated when enemies are killed. Automatically collected. Reduce the Infection Rate. Number generated depends on how fast enemy was killed.
Upper Right: Score Crystal
Increases score. Each one is worth more than the previous (20, 40, 80, etc up to a max of 40960)
Lower Left: 1Up
Lower Right: xCrystal
Increases Infection Rate
Up to 9 levels can be stored. Using Tension converts all bullets currently on the screen into eCrystals, automatically collects all items on screen, and increases shot power for a few seconds. You are NOT invincible while Tension is in effect.
Automatically occurs if you get hit when you have at least 1 Tension remaining. Uses your Tension attack, reduces Tension stock to 0, and increases the Infection Rate by 5.
Berserk/Last Spell mode basically. All bosses and some midbosses have this. Beating it quickly earns a Tension Break bonus to the score and reduces the Infection Rate.
Routes go from A to C. You can be booted down from C to B or B to A if the Infection Rate goes above 40 or if the Twins Rate goes above 80. Choices made invisibly affect the Infection Rate for ROUTE PURPOSES ONLY.
The choice made at the end of stage 3 determines whether you go onto C, B, or A, but not all choices will be available depending on previous choices made and the Infection Rate. You can only move downward once you're on a route, never upward.
True End (Stage 6C/7) special mechanics