Hero System made its first appearance in 1981 as Champions, a RPG designed to recreate the world of four color comics. Since then, Hero Games has attempted to use the underlying mechanics for a wide variety of genres with varying degrees of success. It is currently in its fifth edition and those are the rules referenced here.
I've use it with great success in a number of campaign settings. Most notably Shadowrun, our own version of the Marvel Universe and a Post-Apocalypse game combining Morrow Project, War of the Worlds and Gamma World. In fact, I use it for all my campaigns with the exception of fantasy.
But that doesn't mean it's perfect.
While I was able to use most of the Hero System as is, I found some things 'off' for our style of play. Some concepts didn't work well or needed adjustment. Some 5th edition changes were ill conceived. Like most players, I modified specific sections of the rules to meet my needs.
The following details these house rules for any wishing to play in my campaigns. Each is presented with a brief overview of why the change was needed and how the it affected the system.
The most comprehensive change was in the core system progression. HERO assumes a 2x progression where a 5 point increase represents a doubling of effect. This is most visible with lift limits for Strength (where a 10 STR can lift 100 kg while a 15 STR lifts 200 kg) but is actually felt throughout the system.
The 2x progression produced too steep of a increase for the style of games we play, so the progression was change to 1.53779192x per 5 points. While an odd seeming number, this value was ideal for modeling the range of characters and items in our game while making the best use of 20 or less dice for resolution.
It also matched some important numbers given the Marvel Universe series of comics, an important consideration given that our first HERO System game was a Marvel based superhero campaign. Some of these numbers are: Peak Human Lift at 800 lbs, typical high end super strength characters lifting around 100 tons, and a note indicating that a haymaker from one of those 100 ton lift characters should roughly equal the impact of 500 lbs of TNT.
As an example of this change, a character able to lift 100 tons would have a STR of 60 in the official HERO rules. In these house rules, they would have a STR of 90.
This rather simple change has significant impacts throughout the system, note especially the following areas: Strength, Growth, Density Increase.
The most detailed exceptions in these house rules concern modeling firearms and other weapons with an eye towards increasing their realism- both in the real world and dramatic sense.