https://pakillo.github.io/rgis

This package depends on package velox, which has been removed from CRAN as of 2020-03-17 (see here for more info). While it (hopefully) comes back to CRAN, you will need to install velox before attempting to install rgis, like this (thanks @lbusett for the tip):
devtools::install_version("velox", version = "0.2.0")
Then you can install rgis:
devtools::install_github("Pakillo/rgis")