This GSEA is similar to the original GSEA proposed by Subramanian et al. (2005). The difference lies in the fact that rotation testing is replacing the permutation testing. As shown by D\orum et al. (2009) rotation testing has higher power than permutation testing in case of small sample sizes.
~~ An overview of how to use the package, including the most important ~~ ~~ functions ~~
D\orum, G., Snipen, L., Solheim, M. and S\aeb\o (2009). Rotation Testing in Gene Set Enrichment Analysis for Small Direct Comparison Experiments. Statistical Applications in Genetics and Molecular Biology, 8(1), article 34.
Subramanian, A., Tamayo, P., Mootha, V. K., Mukherjee, S., Ebert, B. L., Gillette, M. A., Paulovich, A., Pomeroy, S. L., Golub, T. R., Lander, E. S. and Mesirov, J. P (2005) Gene set enrichment analysis: A knowledge-based approach for interpreting genome-wide expression pro?les, PNAS, 102, 15545-15550.