It's not a clone, it's derived from the original SimCity source code, which EA licensed under GPL V3 with the added condition that it should not be called "SimCity" without EA's approval. So it's important that all versions of the code include that license and the required provisions.
2.1 Modification. EA hereby grants to OLPC a non-exclusive, non-transferable, non-sub licensable, non-assignable, revocable right and license to modify the Original SimCity as provided by EA for the sole purpose of producing a version of the Original SimCity for distribution on laptops provided through the OLPC Program pursuant to the specifications set forth in Exhibit A ("OLPC SimCity"). All right, title and interest in OLPC SimCity and any interim modifications shall belong solely to EA. OLPC SimCity, and any subsequent versions, will not be distributed by OLPC unless the software meets the requirements set forth in Exhibit A. For the avoidance of doubt, nothing contained in this Agreement shall be deemed to limit or restrict EA’s right to use, modify, sell, distribute or license the Original SimCity in any other manner as EA so desires.
And on a completely unrelated topic:
Q: How do you know there's an elephant hiding under your bed?
http://donhopkins.com/home/micropolis/olpc-ea-contract.pdf
https://code.google.com/p/micropolis/wiki/License
2.1 Modification. EA hereby grants to OLPC a non-exclusive, non-transferable, non-sub licensable, non-assignable, revocable right and license to modify the Original SimCity as provided by EA for the sole purpose of producing a version of the Original SimCity for distribution on laptops provided through the OLPC Program pursuant to the specifications set forth in Exhibit A ("OLPC SimCity"). All right, title and interest in OLPC SimCity and any interim modifications shall belong solely to EA. OLPC SimCity, and any subsequent versions, will not be distributed by OLPC unless the software meets the requirements set forth in Exhibit A. For the avoidance of doubt, nothing contained in this Agreement shall be deemed to limit or restrict EA’s right to use, modify, sell, distribute or license the Original SimCity in any other manner as EA so desires.
And on a completely unrelated topic:
Q: How do you know there's an elephant hiding under your bed?
A: Your face is pressed up against the ceiling!