/usr/lib/realtimebattle/Arenas/Circle.arena is in realtimebattle-common 1.0.8-14.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | scale 1.0
boundary -10.0 -10.0 10.0 10.0
inner_circle 0.9 1.0 0.0 0.0 9.9
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