Seeing topics on revising the rules for cluster rolls and ammo explosions while preparing to start a new campaign must be just coincidence...
In the campaign that I am about to GM, we are going to use some house rules. Oh gee, everybody has house rules! But here's the one that is new, and we are going to playtest to destruction as it were:
There are two parts to this, the fluff and the actual rule.
The rule: on the heat scale, ammo explosions are replaced with "random shutdowns." Ammunition no longer explodes from the heat scale (the "Energy Deficit scale" now, as I'll explain in the fluff). Instead at each point- 19, 23, and 28 on the scale- the player rolls a TAC, floating crit style, at 4+, 6+, and 8+ respectively. What comes up is shutdown; nothing is actually damaged but the selected component is nonfunctional as if it had taken a critical hit. The inactive component stays shutdown until the end of the next turn, where the player rolls to reactivate in the same manner as shutdown mechs may roll to restart. A failed roll means it stays off until the end of the next turn, when a new roll may be made. Likewise the roll is made according to the mech's position on the heatscale (at 4+, 6+, and 8+ respectively, depending on the current number), thus below 19 the component(s) restart automatically. Some notes:
Engines and gyroscopes that are rolled are treated as having received one or more hits. I.e. a mech at 20 heat rolls an engine slot. The mech now builds an extra 5 heat ("energy deficit points" actually, but KISS ok?) until the slot restarts. Rolling the gyroscope is also the same a a critical hit until restarted.
If a location containing ammo is rolled, the location does not explode. Instead, the ammo feeds are shutdown and the ammo cannot be reused until restarted. This also means that ammo in a shutdown location cannot be dumped until the location is restarted. Gauss weapons likewise do not explode, but are nonfunctional until restarted.
If the cockpit is rolled, the mech is treated as if the mechwarrior were unconscious, and the mech is thus immobile until restarted. The mechwarrior is not actually harmed, nor does he roll to stay conscious (and is probably cussing a blue streak an km wide at this point).
While ammo doesn't explode from the heat scale under this system, critical hits from weapon fire are normal. Shooting at a ton of machinegun ammo with a gauss rifle is never wise.
Ok, the Fluff: Some friends and I were talking about Btech (what else?), and they, being young and somewhat tech-saavy thought it strange that units in Battletech run so hot. "Heat is a sign of inefficiency!" they lamented. And so, we formed a logic to explain it.
The heat and heatscale for units is not literally heat. That's how the media packages it for the general public. What it really represents is energy consumption. Btech units generate massive fluctuations of energy, and the engine technology in the Btech universe can produce power only at fairly fixed rates. They are not well suited to generating massive power in a very short period of time (it's an engine, not a bomb). And so, what the journalists and wannabe mechwarriors call heatsinks are really capacitors that store enough energy to buffer the power demands of combat. Mechs don't build up heat, they accumulate an energy deficit. The heatsinks/capacitors are added to mitigate this, but even so combat tends to burn through the supply like a good ol'boy goes through cheap beer. And so, as the deficit rises bad things begin to happen until there is nothing left: upon reaching 30 on the scale the system shuts down, period.
Under this non-canon physics, heat is not normally a problem for battlemechs and aerospace fighters. Their cooling systems are generally very good at managing the heat load. However, some situations- being struck by infernoes or a Plasma Rifle, for instance- require the system to work harder than usual and thus draw more power. Thus, the energy deficit rises and the unit finds itself in a very similar situation as in canon (it is cold comfort that instead of worrying that his autocannon ammo might explode, the mechwarrior watches helplessly as his sensors shut down while facing a lance of angry Capellans).
If this proves workable, we are thinking of making record sheets with a modified "Energy Deficit Scale." To be easier to visualise, I will simply reverse the numbers. Instead of rising on the scale, you go down, from 30 to 0. No real change, it's easier to read that way.
For the TL/DR crowd: On the heatscale substitute "roll for ammo explosion" for "roll TAC/floating crit" and see what turns off.
Everybody tell me what you think. Too much? Too forgiving? Too wierd? What do you think?
