This is embarassing...

[Aerosol]

Code:

gcc Barrel.o Simon.o -o barrel -L/home/aerosol/Tilengine/lib -lTilengine -lm -s -Wl,-rpath,/home/aerosol/Tilengine/lib
/usr/bin/ld: warning: libpng12.so.0, needed by /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_read_info@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_image_width@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_set_sig_bytes@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_read_update_info@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_bit_depth@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_create_read_struct@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_read_image@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_channels@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_init_io@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_color_type@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_PLTE@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_get_image_height@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_destroy_read_struct@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_create_info_struct@PNG12_0'
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/libTilengine.so: undefined reference to `png_sig_cmp@PNG12_0'
collect2: error: ld returned 1 exit status
make: *** [Makefile:42: barrel] Error 1

Here ya go. FYI, I installed Tilengine with "sudo ./install" in Tilengine's root directory, and tried to compile with just "make" in the samples directory.