I've become curious about the 13th Age RPG coming out in March from Pelgrane Press and written by Johnathan Tweet and Rob Heinsoo. I get the sense that while I might not choose the game as my system of preference, that it will likely be filled with stuff to transplant into whatever system I do use.
The Icons story mechanic or whatever one would call it, in which characters at time of creation are given relationships of a sort with from one to three powerful organizations or entities and this influences things throughout the campaign. I can see using that and converting it into something very useful for a Ptolus campaign for tieing the characters more into the goings on in the city. It could serve as plot points and motivators for the player characters.
For example, there are numerous noble families, criminal organizations, political factions, cults/religious orders, and others pushing and pulling at the setting. If a character had some connection, be it positive, conflicted, or negative with an organization that creates all sorts of fun possibilities. Maybe a character has a minor negative (adversarial) connection with the Balacazar Crime Family, when the DM rolls to see if that connection comes into play it might mean the Balacazar's district enforcer is up to something that will impact the character, or it could also mean that someone with a dislike for the Balacazar's might aid or involve the character in something that affects the crime family.
The character may also have conflicted ties to the Inverted Pyramid. Some members are friendly to the character, some not as friendly. At times the character might get aid and at others interference from the group.
The system looks to me like it would really be a boon for getting the players to involve their characters in all sorts of activities.
Backgrounds as it appears they are handled in 13th Age may also prove useful for similar reasons, and the One Unique Thing idea is also worthy of borrowing.
The mechanic for speeding up combat, the Escalation Die, works sort of like the doubling die from Backgammon, except the escalation die just gives an increasing bonus beginning in the second round to all attack rolls for the characters and some more important villains. This sounds like a nice way to handle using flatter math and avoiding grind as opposed to what seems to be happening in the current WotC 5th edition playtest with outrageous amounts of damage escalation.
I suggest looking up the game info and playtest reviews on the web and you may also want to visit BJ Shea's Geek Nation and listen to all 5 episodes of the podcast of Rob Heinsoo running the hosts through character creation and a short bit of play.
There is still a lot I do not know about the 13th Age RPG so I am non-committal about purchasing it until I learn more. Any reader insights are welcome in the comments!