Tux being able to attack bots while he is invisible makes the game too easy to
beat specially because with cooling addons on armor you are able to stay
invisible at all times.

What do you think of having weapon use negate all invisibility?

...What about "Bots can't see you, but they can see the bullets" -- for a brief 
time after shooting you'll be visible and bots are able to counter attack. 

Slow bots like 139 won't be able to see you in the small time frame given, but 
if the bot doesn't wastes too much time seeing you before going to attack 
instance, it might attack you based on where the bullet (or hit for melee) came 
from.