$N$-body simulation in General Relativity

So general relativistic n-body problem is not very studied in the community, but it has a bit of a renewal interest. Then I am not aware of public software, but there is a few group which have solution which kind of works:

https://arxiv.org/abs/1611.07906

https://arxiv.org/abs/1807.11562

https://arxiv.org/abs/1810.05203

https://arxiv.org/abs/1904.07841

Then you would see that the first NR nbody date from the 80s with the work of S. L. Shapiro and S. Teukolsky (85,86).