The game desperately needs an end game, but honestly, I can't think of one that would be satisfying to me.
Does it? Most open world survival games I have played are most fun at the beginning and middle of the game. Late game they tend to get tedious or boring.
IMO the best way to make the game last longer isn't necessarily to add end-game but to draw out more potential in the early and mid game. Right now the game is heavily structured around questing and rushing to T5 is the goal for a lot of people as you get better loot and better trader items.
In order to make each tier effectively last a bit longer I think they can make a few changes.
- You could make Tier 6 POIs by converting some of the longer POIs into Tier 6 such as Dishong Tower as an easy way to increase the game life is to move the goal post.
- If it were me I would do some re-working of armor to offer less overall benefits which would in turn make the game a bit harder and would slow people down a bit more. It doesn't have to be drastic and all at once, but being able to just pop some meds every so often to top off after reducing all the incoming damage seems too powerful.
- Make the POI tiers a bit more distinct in terms of difficulty. Each tier should difficulty check the player and you may need to do a few more lower tier quests to move on to the higher tier ones. I am not talking about a hard cap either, but simply offering a more challenging experience than the previous tier.
I also think adding distractions in between quests would work wonders. I will keep saying it but offering "side-quest" style missions in the form of random events would make people want to explore more and have less drive to line-drive quests.
You are on your way to a quest and your radio picks up a distress SOS that you can go off and tackle for some nice rewards. You are wondering the wilderness and see a downed helicopter with smoke billowing into the air. Bandits are blocking off road access and you can take them out for some good gear or avoid them. Offering more dynamic events than just running from one POI to another to progress is paramount to keeping the game fresh. Instead of adding 27 new POIs, when you only need like 10 to progress each tier, add new events. Heck they don't even have to be randomly spawned. They could just be another POI that spawns in the game with it's own set of rules and interactivity.
Add back a properly working temperature system with seasons and have people to raid clothing stores or harvest cotton to make clothing to stay in peak shape during tougher seasons otherwise it will slow you down having to warm up by a fire, consume more water or avoid the outside heat/cold. These "challenges" are interactive and can be overcome by sheer determination (having to go next to a fire every 15 minutes) or preparation (warm clothing). This would extend the early game a bit and give more things for the player to find/craft to progress smoothly.
Add legendary items or parts quality back into the game to give people a reason to play after they have all the weapons and plenty of ammunition and other assorted items. Getting that perfect 600 weapon was a side project one could delve into and added some reason to loot once you already had the base weapon. Legendary weapons could also work in the regard as you would go out and look for unique weapons with perhaps special modifiers on them that boost aspects of the weapon with each weapon having multiple legendary affixes it can have. Perhaps there is a speed affix for reload, one for damage, etc.
Even some small things like having moon cycles with brighter and darker nights would slow night progression which in turn slows overall progression down a bit.
Now another obvious candidate is a main storyline. If the main story operated in addition to quests whereby additional quests were added in between the grind that would break up the gameplay quite a bit as well and offer some more unique missions to partake in thus extending the game. If done properly, as much as I hate to say it, a main story could add a lot of content to the game for the first few runs at the very least - especially if you could somehow include choices in the missions whereby you can have multiple endings depending on your choices such as side with the duke, kill him, take over his role.
There are a myriad of things that can be done to extend the shelf life of the game. The most important being obviously jars.
