View Full Version : Epsilon Shift (a d20 based sci fi system)

2006-09-19, 03:17 PM
Epsilon Shift is the working title I have for this d20 based system and setting I've created. The setting is my effort in striving for a "realistic" science fiction, one that can draw its history from present time earth. Granted some things have pushed the envelope of technology, faster than light space travel most of all, but the larger part of the technology can be explained as what is within the realm of possibility now, made better by time. So no, this is not Star Wars, and definately not Star Trek, but more along the lines of Bablyon 5, Battlestar Galactica, and many other like Sci Fi's.

Although I borrow elements from d20 modern and future, this setting was partly made when I realized those rules did not adequately work for this setting.

I've got a rulebook which is 24 pages long, so realizing that I can't practically cover it all at once, in this thread I'll cover the basic mechanics changes from the typical d20.

I'm also willing to go into anything in depth if asked. So if you want more details on races, setting descriptions, classes, etc. shoot away with your questions. Because that's the point of this thread, I want put my setting out in the public eye and hear what all of you think.

2006-09-19, 03:30 PM
So biggest change in my system: Armor.

First I'd like to explain the reasoning leading to the changes I'll describe.

Firstly in this setting, millitary technology has developed to the point where powered armor is not only possible, its common gear. This grants the soldier to be able to effectively carry large amounts of armor plating and become a durable combatant like a small vehicle.

The large problem I ran into is that although such armor is going to cover almost the entire body, translating this into a simple bonus to AC didn't cut it. For one it would become practically impossible for low levels to hit each other. Secondly it never acurately represents the wear and tear armor takes when it is repeatedly damaged in combat. Soldiers in power armor can take many hits, but eventually armor is going to break and become ineffective at stopping damage. So I made the armor system a little more complex to represent this.

The two big changes in my armor system:

1) Players keep track of two ACs. The first (which I call Dodge AC) is simply 10+dex modifier+dodge bonuses. If an attack roll fail to meet this AC, the attack misses the character entirely, resulting in no effect. The second AC is called Armor AC. This is the character's Dodge AC+ the AC bonus given by their armor. If an attack beats Dodge AC, and falls short of Armor AC, then it impacts upon the armor, causing damage to the armor. If an attack beats the Armor AC, then the attack falls where the armor wasn't, causing damage straight to the character's hp.

2) Armor now has a hp score to represent its integrity. Above I said how an attack could hit a character's armor. When it does it deals damage to this Armor's Hp. Armor's usually have various DRs against different types of damage. When the Armor's hp is reduced to 0, the armor no longer protects the character. In fact in the case of power armor, it breaks and can encumber the character.

2006-09-19, 07:11 PM
I like the way you've handled the armor thing. I agree with the fact that armor definately needs to be handled differently in sci-fi than in D&D. My Sci-Fi campaign is going to use a system someone developed for d20 Warhammer 40K. Linky. (http://www.geocities.com/skrittiblak/equipment/armour/armourmain.htm)

2006-09-19, 07:33 PM
Yeah a DR can work for armor, the big reason I chose something else is that DR for armor has no good mechanic for hitting someone where there is no armor.

One of the cool things about this Armor with sepererate hp and AC is that I can make distinctions between an armor's coverage and resistance to damage. For instance, a breastplate of particularly tough material vs a full body suit of a lighter armor. The breastplate is going to provide a significantly smaller AC bonus due to the fact it is easier to hit uncovered areas, but is likely to have more hp than the light full covering armor.

I won't breakout the equations unless you want me too, but the way it works is that a full suit of armor provides a high AC bonus. That light suit of armor is going to give a +16 to armor. Take off the helmet arms or legs and that AC bonus is going to drop. The implication here is that armor will usually have to be shot through in order to kill someone, although its not always the case, as one of my PCs, a sniper, can attest.

2006-09-20, 12:57 AM
Okay, significant change number two comes out of the realization that when the character's only chances to avoid damage comes from the slim chance enemies miss a minimal ac somewhat above 10, something needed to be done to keep the PC's alive. Hence class bonus to Dodge AC and improved bonuses from cover.

I wanted to give my game a more tactical feel, the one where cover becomes actually useful as something more than scenery. Where the PC's take up positions at wall corners and victories can be won from strategy and out manuvering. Thus I decided to make cover more than the simple +4 that 3.5 provides. With cover I make two changes.

One is simply allowing PC's to fire around corners without penalty when using the corner as cover, even when conventional line of sight would say they could not shoot. This can be seen as anything from leaning out from the wall and shooting, or simply sticking your gun around the corner and shooting half blind.

Two is I created two types of cover: partial and full. Partial cover is essentially treated the same as normal +4 from 3.5 cover, and represents the simple fact that something is obstructing a clear line of fire to the target, thus making it harder to hit. However I now give the option of taking full cover when it is available. This is like the example I gave of leaning out around the corner, firing, then quickly retreating back. This provides a +8 bonus to dodge AC, but also incurs a -4 penatly to attacks done this way. This penalty can be reduced to -2 from a feat most combatant classes get for free.

2006-09-20, 06:26 PM
Nice rationalisation on the armour front. I also use a similar system for my homebrew D&D game. You forgot(?) to mention how Shields fit into the Armour system; I imagine that this sort of Sci Fi game might have a Shield of some sort occasionally...

The naming is a bit off:
Dodge Armour Class
Armour Armour Class...

The only other aspect of the armour rationalisation I can't quite understand is why you indicate that hits that beat the second Armour Class are assumed to have bypassed the armour; this only works if the armour has such vulnerable points. I would be more inclined to go with 'penetrated.'

If you go with this system you might have to succumb to the reality of 'Hit Locations'. One option is to just assume every attack is aimed at the body. Attacks to the arms, legs and head could be handled through Called Shots (No additional Damage, -4 to AB, only successful on a D20 roll of 16+, otherwise hits the body).

2006-09-20, 08:40 PM
Yeah, I realize the naming convention is a bit off, mostly cause I just say AC all the time that it must have never registered that there was repetition in the acronym.

I left at shields at the moment to show it in its most simplified form. In truth you can add shields to the mechanic by treating them as another layer of armor between dodge and "normal" armor.

So the laying of ac's would then look like this.

D. AC= 10+dex mod+dodge mod
Shield AC= D. AC+ shield AC bonus
A. AC= Shield AC+Armor AC bonus

So it still works, but the more types of armor you stack, the system does get more complex. Fortuantly such instances are rare enough it typically doesn't slow down play.

The reason I say that the shot bypassed armor when it beats Armor AC, is that this represents either hitting where there is not armor, such as an unprotected arm or seam in armor, or hitting a location that has been too weakened by damage to stop the attack.

Also I just say no to called shots. As interesting as the concept would be, and as much as players complain at the occasional logic it represents, it would become a monkey wrench to this mechanic. The distinction between critical hits and called shots is a dim one. The system is already a step more complex than base d20, and I try to streamline things as much as I can.