TL;DR: Looking for recommendations for simple online coop shooters for PS4 without grinding or complex upgrade systems (Dead Nation was perfect; we didn't like Borderlands; Back4Blood card system was too indepth).

I recently moved to the other side of the world and me and my nephew keep in touch by playing videogames once a week. We recently finished Dead Nation and this was the perfect game for us. So, I'm looking for recommendations for similar games.

Games we like(d):

• Dead Nation: perfect match. Mindless shooting, simple upgrades, awesome weapons and enemies and super easy to pick up and play.
• CoD MW2 (current one) Zombie mode.
• CoD Ghost: Extinction.
• Back4Blood: however the card system was to in depth and at the same time too crucial to pass up on. Without the card system it would have been perfect.

Games we didn't like:

• Borderlands: too slow paced.
• Sniper Elite: too slow paced.
• Deep Rock Galactic: we had no clue what was going on.
• GTAV: we liked it for a little bit. However, there weren't many heists for 2 players only. We had trouble finding 2 extra players and they backed out a lot, causing the heists to end adruptly. So, matchmaking took way too long and we stopped playing.

Some specific things we are looking for:

• Must be available on PS4.
• Easy to pickup (we play only 2-3 hours once a week).
• No grinding/complex upgrade systems. For reference, while we like Back4blood the card system was too in depth.
• Preferably but not necessarily a shooter.
• High paced, little story.

Games I was thinking would be nice for us:

• Helldivers 1.
• Dead Island 2.

Thanks in advance!!