Guidelines, Basics.

As there are now people using my engine, I think it is time that I write about the design guidelines I think should be applied.

Syntax

• Stat and item names should only consist of letters, numbers, underscores and spaces. Anything else might break something.
• Currently definitely reserved are # [ ] | ¬ @ = > <  
• If you want to put > or < in your texts, write "& g t ;" or "& l t ;" (without the spaces) as usual for escaping these two characters in XML. If you use the editor, it will take care of this.
• File paths should use /, not \

Interesting Failures

This is a huge pet-peeve of mine. Everyone who has played RPGs on the computer will agree with me: They are all quite linear. Some of them are the purest of railroads (Bioware), others only slightly less so (Bethesda), yet they usually only have a single ending. Or rather, they all have two endings, of which you get to see one all the damn time. It's called "game over screen". Technically, that is an ending. The problem is, it's the most uninteresting ending there is. Some older games tried hard, and had multiple game over screens, which would explain what happened after you died at that specific point, but that still is far from what would be interesting. The point being, that failure in games is completely unheard of. As GlaDOS puts it: "If at first you don't succeed, you fail."
Either you win every single encounter (except those which you lose during a cut-scene) you ever get into, or you have to load and try again. 

Isn't it jarring how surreal that is? Our lives are all but dominated by our failures, yet we continue, we soldier on, and often, it's not much of big deal. People flunk their university exams, but they do not stop existing. They still get a job. They still have kids. And they still fail hundreds of times more. Often, failures are more interesting than successes. People care more about Apollo 13 than about any other of those missions, because it was such a close call, and so much went wrong.

Dear writers, I ask of you: Whenever you write an Action, ask yourself if you can make it a challenge instead, and whenever you write a Failure, try to make it as least as interesting as the success.

Slippery Slope versus Rubber Band

Those two terms are quite common nowadays when talking about game design. I'll give a very brief summary, Sirlin (always worth a read!) has a long essay on the topic for the interested. The first one means that when you are losing, it makes you lose harder. The prime example is any RTS (such as Starcraft or C&C): When you lose a base, you have less money to build units with, to defend your other bases, so you are even more likely to lose more bases. Or Dota: The more enemy heroes you kill, the more experience your hero gets, which makes him more able to kill enemy heroes. If overdone, this ends up with the first hit deciding the match.

Rubber Band means that whenever you are behind, the game helps you catching up. Mario Kart is the most obvious one: Not only do items mostly work against the people in front of you, some of them are exclusively designed so: The blue shell always hits whoever is currently in front, and you can only get lighting bolts if you are far back. Even Starcraft offers Rubber bands: Small armies are generally easier to use, suffer less from splash damage, and it is a lot easier to defend two bases than it is to defend five bases. But if overdone, winning becomes a matter of luck. Imagine a racing game where everyone who is behind gains a 100% speed boost. Who is going to win? Whoever can get in second place a few seconds before the finish line, and use that huge speed boost to win. 

But games written with this engine are not competitive, so they actually do not suffer much from excessive Rubber Banding. I would go so far as to say that huge boons (and a chance to recover) when everything is going to hell make for a much more satisfying story than a slow and painful death. Or in short: All challenges should give out at least as much exp for failures than for successes. If you succeed, that is your reward. You don't need a ton of extra exp on top of that. But if you fail, you usually end up with some disadvantage. To make it sting less, add a good helping of exp.

I tried to implement mechanics into the engine which make it easy to design good games, and hard to design bad ones. The one I want to mention here is the @level="15" stat-reward. Instead of giving out a fixed amount of exp, it will reduce the amount of exp given by a cumulative 20% for every level above 15. The amount given equals exactly enough to go from 15/0 to 16/0. The idea being that you should add this to every failure, and you can guarantee that the player will always keep up with the difficulties, yet not surpass them easily, because it will rubber-bound him back down (yet of course, level-15 exp is quite a lot if you are below level 15).