Glioblastoma (GBM) is an aggressive brain tumor with a median survival of 15 months, largely due to its invasive nature and limited treatment options. Understanding GBM cell migration remains challenging, as current 3D culture models lack reproducibility and fail to mimic native tissue mechanics. To address this, we developed a hyaluronic acid (HA)-based interpenetrating polymer network (IPN) hydrogel with independent tunability of elasticity (G') and viscosity (G''), better replicating brain tissue properties. The hydrogel consists of a photo-crosslinked elastic network and a non-covalent viscous network, allowing precise mechanical control. Mechanical characterization via frequency sweep testing confirmed that our IPN system can match both normal brain tissue and GBM tumor stiffness. The stiff IPN condition (G'~1000 Pa) mimics GBM tumors, while the soft condition resembles healthy brain tissue. Incorporating the dynamic network increased viscoelasticity (tan(d)) threefold over the elastic network alone, without altering the storage modulus. Patient-derived GBM cells encapsulated in the IPN hydrogel exhibited increased proliferation, suggesting a more physiologically relevant tumor environment. Cryosectioning and staining revealed that cells formed tighter spheroids in the stiff gel condition, highlighting the role of mechanical cues in GBM organization. Furthermore, we explored multi-arm polymers with varied crosslinking functionalities to fine-tune hydrogel properties. By independently modulating elastic and viscous modulus, our HA-based IPN model provides a biomimetic platform for studying GBM invasion dynamics, offering potential applications for therapeutic screening.