a system based on the six stats with 5 classes for each stat

[le Redoutable]

1 Devils ====> INT Groom/Counselor/Wizard/Warlord/Lord
2 Undeads ===> CON Janitor/Soldier/Wanderer/Monk/Brute
3 Demons ====> DEX Coward/Thief/Samuraï/Priest/Demon
4 Humans ====> CHA Peasant/Ranger/Drunker/Cook/Druid
5 Dwarves ===> STR Fighter/Paladin/Cavalier/Cleric/Ruler
6 Elves =====> WIS Courtisan/Bard/Archer/Ninja/Assassin

or

1 Devils ====> INT Groom/Counselor/Lord/Warlord/Wizard
2 Undeads ===> CON Soldier/Janitor/Monk/Wanderer/Brute
3 Demons ====> DEX Coward/Thief/Samuraï/Priest/Demon
4 Humans ====> CHA Peasant/Drunker/Cook/Ranger/Druid
5 Dwarves ===> STR Fighter/Cavalier/Cleric/Paladin/Ruler
6 Elves =====> WIS Courtisan/Bard/Archer/Ninja/Assassin

then, you assign a level for each of the five classes from a given stat
( INT means level 1 for Groom, level 2 for Counselor etc )
to access a given Class you need to spend Class Points based on the square of the Class's Level :
Level --- Class Points Expenditure
1 -------------- 1
2 -------------- 4
3 -------------- 9
4 ------------- 16
5 ------------- 25

when you access a given Class you gain Skills or Powers based on the Class Specialty

now to gain the five Classes for each Stat you need 1+4+9+16+25 ===> 55 Class Points;
because 55 is well known to math users, we generate a Stat Level of

1 ----- 1
3 ----- 2
6 ----- 3
10 ----- 4
15 ----- 5
21 ----- 6
18 ----- 7
36 ----- 8
45 ----- 9
55 ---- 10

so, if you have 30 Class Points to spend on Classes ( for one Stat ) you can for example buy a Class Level 5 ( 25 Class Points ) + a Class Level 2 ( 4 points ) + a Class Level 1 ( 12 point )