The idea of the camp is to get some quality training time together, and check out facilities for next year's Commonwealth Games.
Coach Darren Smith want to compare the fitness and skill levels of those players who were in Europe with those who have been back in New Zealand.
Nine of the 28 come from Auckland and North Harbour.
The world league event starts on July 9 and New Zealand are in pool A with world No 2 Australia, 10th-ranked Spain, No 16 Japan and No 17 France.
Pool B contains Olympic runnersup Belgium, bronze medallists Germany, South Africa, Ireland and Egypt.
New Zealand men's hockey training squad for the Gold Coast:
Cory Bennett, James Coughlan, Richard Joyce, George Muir (North Harbour), Marcus Child, Kim Kingstone, Devon Manchester, Arun Panchia, Jared Panchia (Auckland), David Brydon, George Enersen, Nick Haig, Sam Lane, Dominic Newman (Canterbury), Rob Creffier, Shea McAleese, Hayden Phillips, Mac Wilcox (Central), Blair Hilton, Jacob Smith, Harry Miskimmin, Stephen Jenness (Capital), Hugo Inglis, Kane Russell, Nick Ross, Blair Tarrant (Southern). Nic Woods, Leo Mitai-Wells (Midlands).