Skill improvement through skill use is hella cool. 5MORE is not perfect, but it sill leads to more active player, effective action and more unique characters through the sheer force of economics. Why? It might take a while to get there, but bear with me.
5MORE is a minimalistic task-based “improve through use” system. Characters start with no skill list but get EXPERT at them through action and successful experience rolls. So if your character keeps on picking locks or researching musty tomes sooner or later they’ll get that task-specific bonus to the roll. Call of Cthulhu and other Chaosium games have similar systems in place to improve skills, but characters start a skill list.
From now on this game mechanic will be called Action Rewarding Mechanic, ARM in short.
With ARM in place players have another incentive to be more active: in addition to “doing stuff toward an objective” players have their actions rewarded immediately. Action by itself is a reward. While this might lead to players gaming the system and “spamming” skill use (like wieldling as many different weapons as possible through an adventure in Pendragon to get better at all of them, or just plainly practising) the referee can enforce some kind of limitation, like maximum improvement per time or experience gained only per novel or risky activities.
There’s another cause that leads to further specialization: consequences for failure. A failed roll can mean anything from falling from the 5th floor to the worst hangover ever to seriously pissing off the Chevalier de Balibari. If the consequences are negative the character with higher chances of success will probably step up and possibly gain some experience. Of course there’s the choice of choosing an EXPERT character for the task as they’ll have less chances of failure, but the player will be less enticed.
Characters that are not EXPERT but are close are more interested in practising than anybody else, because the real improvement gets progressively nearer with more practice. And since the experience roll decides if the experience is effective or not, characters might (and often do) improve in tasks that are not used often, because of luck (or statistics, pick your favourite). This will of course lead to characters picking up experience in tasks that players never expected, and this will put the experienced characters in the role of the “resident expert” without the player ever planning or wanting it, in their own special quirky ways. Dude, I’m sorry you’re the best at Trapspringing. Or Hypnotizing Snakes. Or Seduction. But someone has to take one for the team, and that someone is you.
And of course more talented characters (those with a high stat related to the task) have more incentives to practice, both because they are better already (which improves in-game prospects) and because after experience is accrued they’ll be even better.
To be fair I think that 5MORE is the part of Adventure Fantasy Game I’m happier with[*]. More action. More focused and unique characters. And still no “picking skills from a long list”.
[*]: Except the Trebouchet of Safety and possibly the Conspicuous Hat.