library(Seurat)
library(ggplot2)
library(ggunchull)

data("pbmc3k")

plotData <- as.data.frame(pbmc3k[["tsne"]]@cell.embeddings)
plotData$cluster <- pbmc3k$seurat_clusters

ggplot(plotData, aes(x = tSNE_1, y = tSNE_2, fill = cluster, color = cluster)) +
  stat_unchull(alpha = 0.5, size = 2) +
  geom_point(size = 0.5) +
  theme(
    aspect.ratio = 1,
    panel.background = element_blank(),
    panel.grid = element_blank(),
    axis.line = element_line()
  )

image.png