“Mendel’s Accountant is the most accurate software available for realistically simulating evolutionary genetic models. It was created by the Institute for Creation Research. Crude forerunners of this software were created earlier by evolutionists, but, since the software did not support their theory, they abandoned it.
Mendel’s Accountant shows that mutations accumulate in a highly linear manner. In other words, almost all mutations do not have a noticeable effect on fitness, they “sit below” the selection threshold. This results in a continuous increase in the number of mutations in each succeeding generation. It means that all genomes decay over time. Natural selection can only remove the worst mutations, and the majority of mutations, the mutations that are only slightly deleterious, accumulate relentlessly and without limit. These “nearly neutral” deleterious mutations accumulate like rust on a car. Even though an individual spot of rust does not affect the fitness of a car, accumulating rust spots will eventually destroy it. There is no way, for the human race or any other species, to get rid of slightly deleterious mutations.
In other words, the arrow of evolution is down, not up.”
Read more here: https://countingtogod.com/mendels-accountant/
See more research regarding the simulation software: https://www.researchgate.net/publication/220101430_Mendel’s_Accountant_A_biologically_realistic_forward-time_population_genetics_program