- Games would last longer. Maybe that's not a "gameplay issue" but League used to have nice 40 minute games. That's what it was based on.
- Because of that, marksmen would actually reach late game. The crit rework was nice but games last too short for marksmen to have any impact.
- Lane phase would feel better, last longer, and allow players to focus on farming/trading instead of constantly leaving lane to skirmish.
- Games would be slightly less snowballing, because towers could provide needed safety and could allow teams to secure picks/more gold and come back from the game if they fought under tower.
- Tower-focused gameplay would be more prevalent, focusing on both solo sieging and team pushing.
- Cheese picks become less effective (NOT the same as off-meta) because it's harder to force the enemy out of lane. (e.g. playing a cheese support to try to abuse enemy and get an early lead).
- On the same note, melee vs ranged becomes slightly less oppressive because your tower is able to last longer and you can fight around tower.
My suggested tower changes (take any of them you want, they don't all have to go together; they probably shouldn't)
Lane towers (T1 and T2) are now slightly different from inhib/nexus towers which I think adds a bit of fun and variety since you have to play around the specific tower abilities:
Outer Turret HP: 3,300
Outer Turret AD: 150 until 4 minutes, +5 per minute, 300 at 34 minutes (punishment for not rotating to clear outer towers is that they can clear minions significantly better later into the game)
Inner Turret HP: 3,300
Inner Turret AD: 180 until 12 minutes, +5 per minute, 300 at 34 minutes
Inhibitor Turret HP: 3,600
Inhibitor Turret AD: 240 until 20 minutes, +10 per minute, 480 at 44 minutes
Nexus Turret HP: 4,000
Nexus Turret AD: 300 until 30 minutes, +10 per minute, 480 at 48 minutes
All turrets EXCEPT outer turrets will now ignore 40% bonus armor.
All towers gain a new item called "Battery Fluctuator:"
"When this tower takes more than (10% of its maximum health) within 8 seconds it will gain 10% damage reduction. This is increased by (1/1.25/1.5/1.75%) for each additional (1% of its maximum health) damage, up to a maximum of 30%.
Additionally, inhibitor and nexus turrets would gain another item called "Bastion:"
"Allied champions within 1200 units gain 4 - 10% damage reduction (depending on distance from tower)."
This damage reduction starts at 4%, increases by 1% per 100 units closer to the tower, and caps at 20%.
This helps tone down damage a little bit without drastically changing the whole game.
Finally, inhibitor and nexus turrets would regenerate much faster. This encourages sieges and pushes to remove the third of the tower instead of randomly stopping when enemies are nearby. Essentially, a third of the tower will regenerate fast enough where it will be completely replenished each fight (if not destroyed), so teams will push towards the next third of the tower health aggressively to prevent the regen, maybe even sacrificing lives for it. However, to compensate, the turret must have not taken any damage or dealt any damage for a certain time. Minions must be cleared to prompt the regen. This makes it so that teams that are extremely behind can't keep holding out by a thread, and it allows game ending when it is actually prompted (i.e. when one team is clearly ahead and the other team is huddled behind tower).
Inhibitor turret health regen: 10 per second, after out of combat for 5 seconds
Nexus turret health regen: 30 per second, after out of combat for 10 seconds
**Note that each third of the tower HP would be shown much more clearly now.**
To compensate for these buffs, tower damage dealt would be slightly increased.
Physical damage users: (100% base AD + 115% bonus AD) (from 100% bonus AD)
Magic damage users: (100% base AD + 70% AP) (from 60% AP)