My players and I were long ago accustomed to the D&D 3.5e ruleset, but now comfortably enjoy 5e's simplicity. Still, there are some rules that we preferred from the previous system that we felt was handled less satisfyingly in 5e. While it doesn't come up often, jumping is one of those rules. 5e's system is straightforward and easy to understand, but leads to guaranteed results with no chance of failure, and it is unintuitive to us that proficiency in Athletics doesn't in any way help jumping. Also, my players and I like rolling dice. For this reason, I have brought forward the 3.5e Jump rules:
When you jump a distance or a height, make an athletics check. A running jump travels a distance up to the result of the check in feet, and up to ¼ of the result in height. From a standing jump, the check's result is halved. The Champion’s Remarkable Athlete ability grants advantage on this check rather than an increase in distance. Multiplying effects like Step of the Wind and the Jump spell multiply the result of this check. For example, with an Athletics check result of 20, a running jump may travel up to 20 feet in distance and 5 feet in height, and a standing jump travels up to 10 feet in distance and 2 feet in height.
A running jump is defined, as in 5e, as 10 feet of movement in a straight line immediately prior to the jump.
In practice, this means that players declare where they intend on jumping to, roll the dice, and then see how far they make it. This uncertain result leads to jumps being seen as an actual hazard, which causes the party to consider backup plans and safety measures for certain perilous jumps rather than treating 10-foot holes as meaningless terrain features that any gnome can consistently clear.
Looking at the numbers, it seems like the expected value (EV) of rolling versus baseline 5e rules is similar or slightly lower (10.5 EV vs 10 base), with a greater difference felt by high Strength characters (13.5 EV vs 16 base) but proficiency in Athletics closes this gap (15.5 vs 16 at level 1, 18.5 vs 18 at level 9). Expertise in Athletics of course increases the EV beyond the base rules. These numbers seem perfectly reasonable to me.
Are there any potential pitfalls* with this house rule? Are there any interactions with other abilities or game effects that might become difficult to reconcile with this change?
*(pun intended, I won't lie to you)