Ad Astra combat

All characters have a number of hit points (hp) equal to 10 + their STR score and +2 per level beyond 1st level. Successful attacks against a character, as well as certain other conditions, will remove hit points temporarily. Characters who, for whatever reason, reach 0 hit points or lower, collapse into unconsciousness and shock, and are at risk of dying. Every round, the character must succeed on a check of his STR + character level, DC 20 every round or die, as described in the Hit Points section of Character Generation.

Most NPC antagonists follow these same rules, but certain NPC antagonists are considered "mooks" (also minions, goons, spear-carriers, etc.) and are not meant to keep fighting after being hit. These characters don't have any hit points, and any successful attack in combat will automatically kill or incapacitate them outright. They are, however, assumed to have all of the other stats as any other character. A soldier bot could be a mook who goes down with only one successful hit, but because he has heavy armor and a high STR, he still makes a more formidable opponent than a regular combat bot.

Each round of combat is conducted in initiative order. Roll 1d20 + DEX for each character to determine initiative order; the character with the highest roll goes first, then the character with the next highest, on down until everyone has moved, at which point you return to the first person in order and do it all again until the combat is over. Resolve any ties by comparing the DEX score. Everyone can do two things during a combat round, (1) move and (2) a move equivalent action, which can be another move, an attack, deflect a ranged attack (if a Knight using his psionic shield), use a skill, etc. All checks or attacks target a Difficulty Class (DC); either a skill DC for skill checks, an opposed skill check result for opposed skill checks, or the target's Armor Class (AC) for attack rolls. Although a move is considered 30 feet, I'm not interested in using a battle-mat, or overly tactical combat, so that's more of an abstraction than anything else. Remember how you used to play D&D back in the 80s without mapping out combat unless it got really excessively complicated due to lots of opponents? That's how space opera games should feel—combat is fast and loose and swashbucklery, not static and grid-based and miniatures game like. To facilitate this, unlike in D&D or most other d20 games, it's not assumed that you must Move and then take your move equivalent action (be it an attack, using psionics, or whatever)—rather, you are assumed to do them at the same time during your turn in the combat round. This means that in d20 terms, all characters are automatically assumed to have the equivalent of the Spring Attack feat.

Although most of the time this doesn’t matter, in case it ever does, the assumed length of a combat round is six seconds.

Melee attacks are made as a STR + To Hit (usually equal to your level—see Character Generation section, but for characters with the Combat Bonus class ability it can be higher). Add your STR bonus to damage as well.  Ranged attacks are made as DEX + Attack Bonus. This includes both shooting a gun as well as throwing something, such as a grenade. If a natural 20 is rolled, you do not need to confirm a critical hit, you automatically do double damage (roll damage dice twice, don't just multiply the result of a single roll.)  If a natural 1 is rolled, you automatically miss, no matter what the total of your bonuses may be.

You may also take damage from other things than simply combat attacks. Here's a few examples:

• Falling: A character takes 1d6 damage for every ten feet fallen. You can reduce this damage by trying to land lightly by making a DEX + Physical skill check with a DC equal to the number of feet fallen. This will result in only half of the damage taken (rounded up.) The Force Surge power can be used to negate falling damage altogether, assuming that there is a steady place to land on below and the distance isn't crazy.
• Hazards: When falling into a hazard, such as spikes, or something like that, add +1 point to the falling damage for every ten feet fallen, max +10.
• Poison: Make a STR + Physical skill check to avoid the damage caused or for half, depending on the poison. The effect depends on the specific poison.
• Extreme Heat or Cold: If not wearing suitable protection, make a STR + Physical skill check once every 10 minutes (DC 15 + 1 per previous check), taking 1d6 damage on each failed save.

Healing.  Characters heal, i.e. gain back the number of lost hit points every hour equal to their character level, or twice this with medical care. (I.e., a 3rd level character will regain 3 lost hit points per hour, or 6 with medical attention.)  To gain the benefits of medical care, you must rest for the entire hour; i.e., stop doing action-movie type stuff. Using Heroism Points, a character can automatically heal themselves of 2d6+2 lost hit points as a "second wind."

Chases.  Related to combat is another staple of the action movie (including space operas)—the chase scene. When one character chases another (either on foot, or in a vehicle) the first thing the GM needs to do is decide how far apart they are. Characters make opposed checks of Physical + DEX (or Agility + DEX for a vehicle.) Whoever wins the opposed check improves his positioning vs. the other participant by his movement allowance. So, if he's running away, he would widen the gap by his movement. If he's chasing, he'd close the gap. Movement (in most cases) is 30 feet for characters on foot. In addition to running, characters can attempt to take other actions, such as fire off a shot with a blaster, dodge through a crowd, knock over crates to throw off pursuit, dodge crates that the person you're chasing knocked over, etc. For these types of actions, use GM rulings to adjudicate—but skill + stat checks for most of them will work. Successful attacks will do damage, as in combat, whereas tactics to slow pursuit may throw pursuers off, force them to make a check to see where you're going, or automatically lose their chase check if you knock them down or something like that.

When a chase is successful is also highly situation dependent. In an open plain or in empty space, you can see for miles and can conceivably chase someone for miles. In a crowded street, it may be easy to lose pursuit. Again, as always, the GM rules based on the situation at hand. Usually if a pursuer catches his prey, the scene changes from a chase scene to a combat scene.

If for some reason you have a character who's extraordinarily fast (i.e., a racial ability, or a mount), give them a bonus on Chase check results equal to +1 for every 10 feet of movement they normally have over 30 ft (rounded down to the nearest 10 feet.)