I hope your English is good (many devs, English is 2nd language), as I'm going to be a bit specific here.
I wouldn't say that it is 'too hard'. Once you've played a time or two, it's 100% beatable. You just have to know which things to spend time on, and which not to. Many games are like this, where you can "earn" a loss by exploring the world (not doing something you need to do by a certain point).
Normally, this is balanced out by the "right choice" being clear to the player. For example. maybe you lose a game if you haven't Purified the Lake by Day 8. "Purify the lake" is a quest you're given on Day 2, after the tutorial, and the game clearly shows you that you should spend one action each day doing it (and you can't take that action more than once per day). This is fine, because it's getting you used to the 'quest system' in that hypothetical game.
However, in this (your) game, the 'quest' is to earn X amount of gold. Except there isn't a button you click to earn gold. It's a series of interlocked levers you have to pull.
And the problem is that what your game teaches the player to do is to summon creatures, and breed them. The tutorial even says "amass many beastkin via breeding". So your game is teaching the player NOT to sell beastkin.
In addition, you have the stamina & energy systems that mean you only get a certain number of breeding session attempts per day, and doing other actions (such as Harvest) detract from that.
The natural result of these interlocking systems is that the player spends 100% of their energy breeding creatures, trying to get babies. Because that's what the game told them to do. And common sense would be that you breed the parents, get the baby, then consider using the parent with worse stats than the baby to complete a quest.
This entire logic chain means that the game has a Ludonarrative Dissonance. That is, what makes sense to do based on the narrative, genre, and mechanics of the game are not actually the optimized choice for what to do.
Instead, if you want to earn money fast, you just buy every slave that shows up, have them fuck for xp (who cares about babies), and sell them off in groups whenever your quests are about to time out. And the problem is that is entirely contrary to the conceptual purpose of the game (breed stuff).
So, how do you fix this? Well, as I mentioned, this is a series of interlocked levers that you're presenting to the player, tied to the mechanics of the game.
- You could raise the baby rates. If fertility started at 100%, you'd get tons and tons of babies, which would mean that the player will naturally focus on the stats/quests aspect of the game (because the babies come no matter what).
- You could TELL the players to just buy & train beastkin to turn in for quests (delete all the game text about trying to be a breeder).
- You could remove the tax system, so the player is not required to earn ever-increasing amounts of money.
- You could implement Rogue-Lite mechanics (this it the route chosen by breeder-y game Portals of Phereon) - where you still earn things for 'your account' upon Game Over.
You can even do more than one of them. But as a game designer, the question should always be "what does this add to the game?". The tax system creates a sense of urgency. But does the game NEED a sense of urgency? Breeders of the Nephilym is just a breeding sandbox game. No tax, but does have quests. It's still fun, even without a lose condition. Breeding Season, Cloud Meadow, Breeding Farm, and more all kept the weekly payment approach. So obviously you can have a game with it - but my argument is that it adds nothing to a game that should be focused on breeding, unless earning money is a natural result of doing the breeding (which it isn't - earning money is a result of the quest board. Fucking for XP is how you do quests; not breeding - because the quest board doesn't want level 1 beastkin).
So, I quickly noticed #2 and #3. The problem? These 2 mechanics (steadily increasing rates), encourage you to pair the same beastkin together over and over again. Which actually conflicts with Doing Quests. if you're breeding Laya with Mikey, and they have a 5% chance to have a baby, and fail. Then 10% fails. Then 18% fails. Then 32% fails. You have 1 day left on a quest, and you can send Mikey off to get some cash.
Do you sell Mikey, or keep breeding him with Laya to get a baby?
You have 2 game mechanics that conflict with each other here, forcing the player to make a decision. That isn't inherently bad. The problem here is that it's a false choice. The player doesn't REALLY have a decision to make, because if they keep Mikey for breeding, they are a step closer to losing the game.
It's like when you play Matrix: Path of Neo. Morpheus offers you the red pill or the blue pill. Great! Player agency. Pick the blue pill. Game over. It wasn't really a choice. If you want to play the game, you HAVE to pick the red pill.
And here, if you want to play the game, you HAVE to sacrifice Mikey to the Quest Board. So if you HAVE to do it, why even give the player the choice? Why give the increasing odds every attempt? Why make the player get invested in keeping pairings the same for the increasing chance of (FINALLY) getting a baby.
Now, this is also largely a problem with the low base rate. You're "never" going to get a baby on the first try, until you get beastkin with WAY higher stats. This was aproblem in Breeding Season, too. You basically HAD to rack up repeat-pairing bonuses in order to get a reasonable chance at babies. At least until you got to the mid-game (and then you were getting 5+ babies/day, and it was a non-issue anymore).
As far as #1 goes (harvest items & bonus chance stacking). My main comment here would be that the items should say EXACTLY how they work. Stamina potions don't say how much stamina they give. The stat-boosting ones don't say how much stat boost they give. Everything should clearly say in the description how it affects the game's mechanics, so the player can make an informed decision. I didn't really even touch potions my first time through, because of how vaguely worded they were.
So, again, I would not say that your game is HARD. I would say that your game just has a learning curve. The player needs to learn that what the game SAYS to do is wrong. Do not do that. Do a different thing.
The difficulty if you do what the game says is VERY hard. The difficulty if you just buy slaves, level them up, and turn them in for quests, is actually very easy.
