What is Bonus Time?
In the Jack's 55th Birthday mode, you are ranked by how much time you have left on the clock when you finish the level. Bonus time is added to a second clock- the main clock doesn't move until the bonus clock runs out. If you keep adding bonus time, the main clock can remain motionless for actual minutes on end. Bonus time cannot, however, turn back the main clock. If you have 8 minutes left on the main clock, and 4 minutes of bonus time when the mission ends, you still get the rank & reward for 8 minutes, not 12.
How do you get Bonus Time?
The only way to acquire Bonus time is by attacking monsters. Each weapon gives a different time reward, but the mechanics are the same for each:
Every non lethal attack that hits gives you a small amount of Bonus time. This amount is the same no matter what creature you are attacking.
You get a larger amount of bonus time for every attack which kills an enemy. This amount is different for different enemies, but in general harder enemies grant more time. This bonus does NOT stack with the bonus you get just for making a successful hit (This is an important factoid to remember, as it means the multiplier given by the Time Bonus A skills does not affect lethal hits at all).
Is there any other way to get Bonus Time?
Sort of. There's no other way to generate Bonus Time, but destroying one of the mobile Mr. Everywhere statues floating around the levels will double the amount of time on your bonus clock. If you don't have any bonus time, this does nothing, but pair up this multiplier with the Blue Blaster and some canny planning, and you can then saunter through the rest of the level with ease.
How Much Bonus Time Does Each Attack Grant?
Non Lethal Hit
Blobula & Marguerite
* The burner's incredibly high hits-per-second and low damage make it a very efficient way to harvest bonus time.
**Note that it doesn't matter how much of the blast hits the monster. Whether it's a point blank shot, or just a single winging hit, the bonus time adds up the same. The rounding errors that creep in can skew the time a few hundredths of a second this way or that, but not enough to be useful.
How Do Skills Affect Bonus Time?
With a flat percentage. Time Bonus a1 adds 10% to all bonus time granted from non-lethal hits, Time Bonus b1 ads 10% to all lethal hits (so if you're rocking the Crowbar + Brawler Combo, you'll want to stick with Time Bonus b). Each of those skills has a level 2 version, which adds 30% more bonus time. If both levels are equipped, you get a flat 40% additional (no compound interest here).
The only other skill that grants bonus time is the Masochist skill, which grants time for being hit by enemies. However, the time granted is directly proportionately to the amount of health you lost- so if you're buffed up enough to withstand multiple hits, this probably isn't doing you much good.
There's also the Infinite Ammo skill, which reduces your time bonuses, but since time bonuses are the most critical thing you can get, you should probably not use this skill. Besides, the Gold Blaster comes with infinite ammo.