It’ll be a puzzle adventure game, because the characters aren’t fighters. Much like Heavy Rain, it’ll be a mature adventure game (without the QTEs), so if you’ve seen the show, characters can die and you have to solve the situation like Curtis who’s always the dues ex machina of the show.
There aren’t many gameplay models for such a game, which is why it would involve lots of different gameplay.
You have to use everyone’s powers sometimes simultaneously, to solve the situation.
Each situation will be unpredictable, and there won’t be a goal set forth. You have to let the events pass, and figure out any suspicions with using the different character’s powers. Then when the situation starts occurring, you can prevent it.
There might be some predictable goals and missions, like stop a gang leader, than in normal shooting games would be easy, but with these characters it’s a whole other ballpark of gameplay opportunities.
You would not revisit any situations previously happened on the show, because you already know how to solve every situation. It’ll be in a unique time period of itself.
You’ll have parts where all the characters are in the situation, or just a couple, or just yourself. The single character situations will play just like Indigo Prophecy episodes, focused around their story.
You can play as all the characters. It could be pseudo-realtime/turn-based (KOTOR) when in the heat of action. You don’t order other characters to help you, you have to do it yourself. No one’s the leader yet. This avoids the game feeling devoid of challenge or excitement.
Each character’s gameplay is obviously unique, but has to be a challenge to the player so the game can be fun:
Curtis turns back time, but you have to stop at the exact right moment. It’ll be like a reverse slideshow of pictures, and you have to stop at the most opportune time. You don’t get many tries if you stop at the wrong time, like maybe about 3, because each try can drain your “mana”. He's also the only character who can be capable in a fist-fight, so he could be the front runner in a combat situation.
Alisha charms, so she has to charm the right person at a non-combat part of a situation. Basically, she plays as a distraction, to move the person away from the situation, not really to have to sex with them. Since she’s defenseless, maybe could use Simon as a combo to become invisible and whack the dude on the back of the head before she gets in danger.
Kelly can hear minds, so like a detective game, she can pick up certain bits of dialogue from people’s minds, (Siren New Translation), and find out who might be the aggressor/attacker in the situation.
Simon can turn invisible, so he’s probably the most useful because you can have stealth gameplay and also have everyday objects as weapons.
Nathan is like a tank, he’s invincible, and you can use him as a shield if there’s a gangster with a gun. But when he dies, there’ll be a recharge time of 2 minutes for revival. That’s when you need the other characters to take over, and not let his death be in vain.
Nikki, the newest character, can teleport. She is actually the most helpful in a combat situation, and can be used to transport other characters. She will be the most resistant in combat situations because of her teleporting, but you have to teleport before a gun’s fired because a) she doesn’t have bullet time, so she can’t dodge; b) she has no Spidey sense so she can’t teleport at the exact right moment. Before a gangster reaches for a gun in his pants, there will be a slow-mo, but it won’t be a QTE. You have to pick the location with an arrow (Brothers in Arms) to where you want to teleport.
That's it for now, this was all just off the top of my head. It just came to me, when I was on the toilet, as you do...with all brainstorming sessions.
Just a fun little time waster.