I actually got really far and completed the bloodline upgrades, but mostly because i would get to around the dragonslayer and then the game would prompt me to lay another egg to upgrade and get farther faster. but then once i had fully upgraded, there wasnt much point in starting again, and the exp still slowed way down. I was only getting to level like, 50 in the early stages. I think i got to 80 on my most recent one with the bloodline maxed out but it still slows way down.