PerSonas and its sequel Arkana are a pair of maps which both implemented a very clever mechanic called the perSona switch. At the start of the game, players pick two heroes; each is called a persona.
At any point during the game, pressing 'Q' will activate a perSona switch, instantly replacing one persona with the other. Switching preserves life and shield percentages, while removing buffs and disjointing projectiles, so the ability has intrinsic value.
Each persona has an independent ability set and cooldowns, so switching allows players to perform combos, or enact cunning escapes.
There is no mana in the game, so players are free to spam their abilities (from both personas) as much as they like. Instead, heroes have shields, which absorb 70% of incoming damage, and quickly regenerate while out of combat.
Like mana, maximum shields typically measure 50-80% of a hero's maximum life, but are a separate stat which grows and can be upgraded separately. Some abilities are more effective at depleting shields, or cost shields to cast. As you can imagine, shields are completely necessary to weather the constant ability spam and low cooldowns.
There are about 50 items in the game; roughly 30 basic and 20 recipes. There is very little overlap amongst the selection, so if you want dps or tankiness it's very clear what's best to get. However, because a player's inventory is shared between two personas, there is still plenty of thinking involved when deciding what to build.
The map itself is relatively sparse, populated by the occasional weak jungle camp. The camps grow in strength as the game progresses, but not significantly compared to the heroes. The terrain was given more attention than most maps, with plentiful custom textures and imports, which made for a distinct look.
Passive hero abilities like temporary bonus attack rate for using abilities, or shield regeneration for nearby allies, when learned on one persona will apply to both, encouraging players to pick complimentary characters.
The depth of choice at the picking phase is what gives PerSonas a great deal of replayability, and a remarkably higher skill ceiling than the clean and straightforward heroes would otherwise provide.
There are two victory conditions; either push past the enemy towers and kill their leader (a powerful unit rather than a building), or accumulate enough kills against the enemy team. The kills condition is evoked most often in actual gameplay, and is usually unsatisfying and anti-climatic.
The relative ease of learning the heroes compared to the amount of depth available from them is phenomenal; almost too good to be true when contrasted with trying to introduce a cast of 100+.
PerSonas had great potential, but unfortunately development was short-lived and the concept has been left gathering dust. With more depth in the heroes, a little more item variety, and one or two supplementary mechanics in the jungle, PerSonas could have really taken off.