King of the Hill - 6000 Points
This challenge is nigh-unachievable. Not completely unachievable, as I have seen a rare 6K+ plus player. However, after weeks of playing KotH, and being top score at least 5 times, the closest I've ever come is ~5K.
If you play too well, you win too fast. If you don't, you can't achieve anywhere close to 6K. The odds of two teams being evenly matched to allow a player to dominate-but-not-too-fast are rarer still. And yes, I've reconned, supported, rezzed, and sweated like an unemployed Adderall addict, to no avail.
Even close games don't work - we lost by ONE point, twice, I was top in board, and still only achieved ~5K. Nearly every match ends with players topping in the 4,000's. Excluding those players with the "great gaming chair" that win on kills alone of course... claiming it's "ez".
I cannot fathom what 10K was like in the beta/release, or why that was selected as a threshold beyond absurd participation incentivization. But if you want players to actually have some sense of satisfaction in getting these challenges done, then you could tune them better. It's not fun, or a sense of accomplishment, it's just frustrating and makes me want to play something else for the effort involved.